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Background Body mass index (BMI) shows strong continuity over childhood and adolescence and high childhood BMI is the strongest predictor of adult obesity. Genetic factors strongly contribute to this continuity, but it is still poorly known how their contribution changes over childhood and adolescence. Thus, we used the genetic twin design to estimate the genetic correlations of BMI from infancy to adulthood and compared them to the genetic correlations of height. Methods We pooled individual level data from 25 longitudinal twin cohorts including 38,530 complete twin pairs and having 283,766 longitudinal height and weight measures. The data were analyzed using Cholesky decomposition offering genetic and environmental correlations of BMI and height between all age combinations from 1 to 19 years of age. Results The genetic correlations of BMI and height were stronger than the trait correlations. For BMI, we found that genetic correlations decreased as the age between the assessments increased, a trend that was especially visible from early to middle childhood. In contrast, for height, the genetic correlations were strong between all ages. Age-to-age correlations between environmental factors shared by co-twins were found for BMI in early childhood but disappeared altogether by middle childhood. For height, shared environmental correlations persisted from infancy to adulthood. Conclusions Our results suggest that the genes affecting BMI change over childhood and adolescence leading to decreasing age-to-age genetic correlations. This change is especially visible from early to middle childhood indicating that new genetic factors start to affect BMI in middle childhood. Identifying mediating pathways of these genetic factors can open possibilities for interventions, especially for those children with high genetic predisposition to adult obesity. This study was conducted within the CODATwins project. Support for collaborators: Colorado Twin Registry is funded by NIDA funded center grant DA011015, & Longititudinal Twin Study HD10333; Author Huibregtse is supported by National Institute on Drug Abuse (5T32DA017637) and National Institute on Aging (5T32AG052371). Finnish Twin Cohort is supported by the Academy of Finland (grants 312073 and 336823) and the Sigrid Juselius Foundation. Michigan State University Twin Registry was supported by National Institute of Mental Health (NIMH) (R01-MH081813, R01-MH0820–54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01, 1R01-MH118848-01), Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD) (R01-HD066040) and MSU Foundation (11-SPG-2518). PETS was funded by the Australian National Health and Medical Research Council (grant numbers 437015 and 607358); the Bonnie Babes Foundation (grant number BBF20704); the Financial Markets Foundation for Children (grant number 032-2007); and the Victorian Government’s Operational Infrastructure Support Program. We acknowledge The Swedish Twin Registry for access to data. The Swedish Twin Registry is managed by Karolinska Institutet and receives funding through the Swedish Research Council under the grant no 2017-00641. TEDS was supported by a program grant to RP from the UK Medical Research Council (MR/M021475/1 and previously G0901245), with additional support from the US National Institutes of Health (AG046938). The West Japan Twins and Higher Order Multiple Births Registry was supported by Grant-in-Aid for Scientific Research (B) (grant number 20H04019) from the Japan Society for the Promotion of Science. Open Access funding provided by University of Helsinki including Helsinki University Central Hospital.

Objectives This study targeted public health nurses in a Japanese municipality that had newly adopted the core components of the Finnish system to provide continuous support to families with children until preschool. It sought to analyze changes in their perceptions for activities in maternal and child health care before and after the adoption.Methods Relevant data were collected through semi-structured focus group interviews, following an interview guide, conducted from September to October 2020. The study protocol was approved by the Ethics Committee of Osaka City University in Japan.Results A total of 12 public health nurses participated. Prior to the adoption of the system modelled on Finnish practice, these nurses were dedicated to addressing the risks regarding families with children (especially those at high risk) through continuous engagement. However, they were hesitant to proactively engage with families at lower risk as non-continuous, one-off engagements resulted in a patchwork response. After the system was adopted, the nurses became aware of the trust cultivated with families under their care, which included those at lower risk, that enabled them to respond to the changing needs flexibly. The nurses recognized that they had acquired the capability to notice the subtle signs of changes, engage more proactively with the families under their care, and deliver the necessary preventive interventions at an early stage. They also demonstrated joy and satisfaction derived from the growth of children and mothers under their care, as well as keen awareness of the need to improve their professional skills, even though they were busy.Conclusion These findings indicate that the continuous support system modelled on the core components from Finland enables public health nurses to proactively engage with families at lower risk and deliver preventive interventions at an early stage. The system also motivated Japanese public health nurses who found greater pleasure in their work.

We investigated the heritability of educational attainment and how it differed between birth cohorts and cultural-geographic regions. A classical twin design was applied to pooled data from 28 cohorts representing 16 countries and including 193,518 twins with information on educational attainment at 25 years of age or older. Genetic factors explained the major part of individual differences in educational attainment (heritability: a(2)=0.43; 0.41-0.44), but also environmental variation shared by co-twins was substantial (c(2)=0.31; 0.30-0.33). The proportions of educational variation explained by genetic and shared environmental factors did not differ between Europe, North America and Australia, and East Asia. When restricted to twins 30 years or older to confirm finalized education, the heritability was higher in the older cohorts born in 1900-1949 (a(2)=0.44; 0.41-0.46) than in the later cohorts born in 1950-1989 (a(2)=0.38; 0.36-0.40), with a corresponding lower influence of common environmental factors (c(2)=0.31; 0.29-0.33 and c(2)=0.34; 0.32-0.36, respectively). In conclusion, both genetic and environmental factors shared by co-twins have an important influence on individual differences in educational attainment. The effect of genetic factors on educational attainment has decreased from the cohorts born before to those born after the 1950s. This study was conducted within the CODATwins project. We thank Wendy Cozen, University of Southern California, for sharing data with us. Funding for collaborators: Netherlands Twin Register acknowledges the Netherlands Organization for Scientific Research (NWO) and MagW/ZonMW grants 904-61-090, 985-10-002, 912-10-020, 904-61-193,480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192; VU University's Institute for Health and Care Research (EMGO+); the European Research Council (ERC - 230374), the Avera Institute, Sioux Falls, South Dakota (USA). Data collection and analyses in Finnish twin cohorts have been supported by ENGAGE - European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, Grant Agreement Number 201413, National Institute of Alcohol Abuse and Alcoholism (Grants AA-12502, AA-00145, and AA-09203 to R J Rose, the Academy of Finland Center of Excellence in Complex Disease Genetics (Grant Numbers: 213506, 129680), and the Academy of Finland (Grants 100499, 205585, 118555, 141054, 265240, 263278 and 264146 to J Kaprio). Since its origin the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a non-profit Association for Scientific Research in Multiple Births (Belgium). Anthropometric measurements of the Hungarian twins were supported by Medexpert Ltd., Budapest, Hungary. The Murcia Twin Registry is supported by Fundacion Seneca, Regional Agency for Science and Technology, Murcia, Spain (08633/PHCS/08, 15302/PHCS/10 & 19479/PI/14) and Ministry of Science and Innovation, Spain (PSI2009-11560 & PSI2014-56680-R). K Silventoinen is supported by Osaka University's International Joint Research Promotion Program. We acknowledge The Swedish Twin Registry for access to data. The Swedish Twin Registry is managed by Karolinska Institutet and receives funding through the Swedish Research Council under the grant no 2017-00641. This research was facilitated through access to Twins Research Australia, a national resource supported by a Centre of Research Excellence Grant (ID: 1079102), from the National Health and Medical Research Council. California Twin Program was supported by The California Tobacco-Related Disease Research Program (7RT-0134H, 8RT-0107H, 6RT-0354H) and the National Institutes of Health (1R01ESO15150-01). The Carolina African American Twin Study of Aging (CAATSA) was funded by a grant from the National Institute on Aging (grant 1RO1-AG13662-01A2) to K. E. Whitfield. Colorado Twin Registry is funded by NIDA funded center grant DA011015, & Longititudinal Twin Study HD10333; Author Huibregtse is supported by 5T32DA017637 and 5T32AG052371. Washington State Twin Registry (formerly the University of Washington Twin Registry) was supported in part by grant NIH RC2 HL103416 (D. Buchwald, PI). Vietnam Era Twin Study of Aging was supported by National Institute of Health grants NIA R01 AG018384, R01 AG018386, R01 AG022381, and R01 AG022982, and, in part, with resources of the VA San Diego Center of Excellence for Stress and Mental Health. The Cooperative Studies Program of the Office of Research & Development of the United States Department of Veterans Affairs has provided financial support for the development and maintenance of the Vietnam Era Twin (VET) Registry. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the NIA/NIH, or the VA. The NAS-NRC Twin Registry acknowledges financial support from the National Institutes of Health grant number R21 AG039572. Korean Twin-Family Register was supported by the Global Research Network Program of the National Research Foundation (NRF 2011-220-E00006). Osaka University Aged Twin Registry is supported by grants from JSPS KAKENHI JP (23593419, 24792601, 26671010, 24590695, 26293128, 16K15385, 16K15978, 16K15989, 16H03261).

Kaprio, Jaakko/0000-0002-3716-2455; Huibregtse, Brooke M./0000-0003-0977-7249; Magnusson, Patrik KE/0000-0002-7315-7899; ONCEL, Sevgi YURT/0000-0002-0990-292X; Aliev, Fazil/0000-0001-8357-4699; Silventoinen, Karri/0000-0003-1759-3079; van Beijsterveldt, Toos/0000-0002-6617-4201; Knafo-Noam, Ariel/0000-0003-0613-1960; Latvala, Antti/0000-0001-5695-117X; Loos, Ruth/0000-0002-8532-5087; Bartels, Meike/0000-0002-9667-7555; Sund, Reijo/0000-0002-6268-8117; Willemsen, Gonneke/0000-0003-3755-0236 WOS:000560040700031 PubMed: 32409744 Genetic factors explain a major proportion of human height variation, but differences in mean stature have also been found between socio-economic categories suggesting a possible effect of environment. By utilizing a classical twin design which allows decomposing the variation of height into genetic and environmental components, we tested the hypothesis that environmental variation in height is greater in offspring of lower educated parents. Twin data from 29 cohorts including 65,978 complete twin pairs with information on height at ages 1 to 69 years and on parental education were pooled allowing the analyses at different ages and in three geographic-cultural regions (Europe, North America and Australia, and East Asia). Parental education mostly showed a positive association with offspring height, with significant associations in mid-childhood and from adolescence onwards. In variance decomposition modeling, the genetic and environmental variance components of height did not show a consistent relation to parental education. A random-effects meta-regression analysis of the aggregate-level data showed a trend towards greater shared environmental variation of height in low parental education families. In conclusion, in our very large dataset from twin cohorts around the globe, these results provide only weak evidence for the study hypothesis. Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) [340-2013-5867]; Stockholm County Council (ALF-projects)Stockholm County Council; Swedish Heart-Lung FoundationSwedish Heart-Lung Foundation; Swedish Asthma and Allergy Association's Research Foundation; Swedish Research CouncilSwedish Research Council [2017-00641]; Netherlands Twin Register acknowledges the Netherlands Organization for Scientific Research (NWO)Netherlands Organization for Scientific Research (NWO) [904-61-090, 985-10-002, 912-10-020, 904-61-193,480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008]; European Research CouncilEuropean Research Council (ERC); Avera Institute, Sioux Falls, South Dakota (USA); KNAW Academy Professor Award [PAH/6635]; ENGAGE - European Network for Genetic and Genomic Epidemiology [201413]; National Institute of Alcohol Abuse and AlcoholismUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Alcohol Abuse & Alcoholism (NIAAA) [AA-12502, AA-00145, AA-09203]; Academy of Finland Center of Excellence in Complex Disease GeneticsAcademy of Finland [213506, 129680]; Academy of FinlandAcademy of Finland [100499, 205585, 118555, 141054, 265240, 263278, 308248, 312073, 264146]; Fund of Scientific Research, Flanders and Twins, a non-profit Association for Scientific Research in Multiple Births (Belgium); Cancer Research UKCancer Research UK [C1418/A7974]; European UnionEuropean Union (EU) [HEALTH-F4-2007-201413]; BioSHaRE EU [HEALTH-F4-2010-261433, POCI/DES/56834/2004]; Portuguese agency for research (The Foundation for Science and Technology [FCT]); Krkkale University Research Grant: KKU [2009/43]; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114C117]; Osaka University's International Joint Research Promotion Program [R01 HD068435, R01 MH062375]; National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R21 AG039572]; California Twin Program; California Tobacco-Related Disease Research ProgramUniversity of California System [7RT-0134H, 8RT-0107H, 6RT-0354H]; Carolina African American Twin Study of Aging - National Institute on Aging [1RO1-AG13662-01A2, DA011015, 5T32DA017637, 5T32AG052371]; Michigan State University [R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01]; National Institute of Mental Health (NIMH)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01-HD066040]; Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD) [11-SPG-2518]; MSU Foundation - National Institute of Mental Health [R01 MH58354, AA023322, HD081437]; Vietnam Era Twin Study of Aging; National Institute of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [NIA R01 AG018384, R01 AG018386, R01 AG022381, R01 AG022982]; VA San Diego Center of Excellence for Stress and Mental Health; Cooperative Studies Program of the Office of Research & Development of the United States Department of Veterans Affairs; Global Research Network Program of the National Research Foundation [NRF 2011-220-E00006]; National Research Foundation of KoreaNational Research Foundation of Korea [NRF-371-2011-1 B00047]; West Japan Twins and Higher Order Multiple Births Registry [15H05105]; Japan Society for the Promotion of ScienceMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science; Centre of Research Excellence Grant [1079102]; National Health and Medical Research CouncilNational Health and Medical Research Council of Australia [240994]; [266592] This study was conducted within the CODATwins project (Academy of Finland #266592). The CATSS-Study is supported by the Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) framework grant no 340-2013-5867, grants provided by the Stockholm County Council (ALF-projects), the Swedish Heart-Lung Foundation and the Swedish Asthma and Allergy Association's Research Foundation. The Swedish Twin Registry is managed by Karolinska Institutet and receives funding through the Swedish Research Council under the grant no 2017-00641. Netherlands Twin Register acknowledges the Netherlands Organization for Scientific Research (NWO) and MagW/ZonMW grants 904-61-090, 985-10-002, 912-10-020, 904-61-193,480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192; Amsterdam Public Health (APH); the European Research Council (ERC - 230374), the Avera Institute, Sioux Falls, South Dakota (USA) and the KNAW Academy Professor Award (PAH/6635) to DIB. Data collection and analyses in Finnish twin cohorts have been supported by ENGAGE - European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement number 201413, National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145, and AA-09203 to R J Rose, the Academy of Finland Center of Excellence in Complex Disease Genetics (grant numbers: 213506, 129680), and the Academy of Finland (grants 100499, 205585, 118555, 141054, 265240, 263278, 308248, 312073 and 264146 to J Kaprio). Since its origin the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a non-profit Association for Scientific Research in Multiple Births (Belgium). Gemini was supported by a grant from Cancer Research UK (C1418/A7974). Data collection and research stemming from the Norwegian Twin Registry is supported, in part, from the European Union's Seventh Framework Programmes ENGAGE Consortium (grant agreement HEALTH-F4-2007-201413, and BioSHaRE EU (grant agreement HEALTH-F4-2010-261433). Madeira data comes from the following project: Genetic and environmental influences on physical activity, fitness and health: the Madeira family study Project reference: POCI/DES/56834/2004 Founded by the Portuguese agency for research (The Foundation for Science and Technology [FCT]). S.Y. oncel and F. Aliev are supported by Krkkale University Research Grant: KKU, 2009/43 and TUBITAK grant 114C117. K Silventoinen is supported by Osaka University's International Joint Research Promotion Program. The Boston University Twin Project is funded by grants (#R01 HD068435 #R01 MH062375) from the National Institutes of Health to K. Saudino. California Twin Program was supported by The California Tobacco-Related Disease Research Program (7RT-0134H, 8RT-0107H, 6RT-0354H) and the National Institutes of Health (1R01ESO15150-01). The Carolina African American Twin Study of Aging (CAATSA) was funded by a grant from the National Institute on Aging (grant 1RO1-AG13662-01A2) to K. E. Whitfield. Colorado Twin Registry is funded byNIDA funded center grant DA011015, & Longitudinal Twin Study HD10333; Author Huibregtse is supported by 5T32DA017637 and 5T32AG052371.; The Michigan State University Twin Registry has been supported by Michigan State University, as well as grants R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01 from the National Institute of Mental Health (NIMH), R01-HD066040 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD), and 11-SPG-2518 from the MSU Foundation. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the NIMH, the NICHD, or the National Institutes of Health. The University of Southern California Twin Study is funded by a grant from the National Institute of Mental Health (R01 MH58354). The Texas Twin Project is currently funded by grants AA023322 and HD081437 from the National Institutes of Health. Vietnam Era Twin Study of Aging was supported by National Institute of Health grants NIA R01 AG018384, R01 AG018386, R01 AG022381, and R01 AG022982, and, in part, with resources of the VA San Diego Center of Excellence for Stress and Mental Health. The Cooperative Studies Program of the Office of Research & Development of the United States Department of Veterans Affairs has provided financial support for the development and maintenance of the Vietnam Era Twin (VET) Registry. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the NIA/NIH, or the VA. The NAS-NRC Twin Registry acknowledges financial support from the National Institutes of Health grant number R21 AG039572. Korean Twin-Family Register was supported by the Global Research Network Program of the National Research Foundation (NRF 2011-220-E00006). South Korea Twin Registry is supported by National Research Foundation of Korea (NRF-371-2011-1 B00047). The West Japan Twins and Higher Order Multiple Births Registry was supported by Grant-in-Aid for Scientific Research (B) (grant number 15H05105) from the Japan Society for the Promotion of Science. This research was facilitated through access to Twins Research Australia, a national resource supported by a Centre of Research Excellence Grant (ID: 1079102), from the National Health and Medical Research Council. Longitudinal Israeli Study of Twins was funded by the Starting Grant no. 240994 from the European Research Council (ERC) to Ariel Knafo.

Loos, Ruth J F/0000-0002-8532-5087; Huibregtse, Brooke M./0000-0003-0977-7249; Kandler, Christian/0000-0002-9175-235X; Hjelmborg, Jacob/0000-0001-9630-9149; mangino, massimo/0000-0002-2167-7470; Siribaddana, Sisira/0000-0001-5821-2557; Plomin, Robert/0000-0002-0756-3629; Latvala, Antti/0000-0001-5695-117X; Kaprio, Jaakko/0000-0002-3716-2455; Willemsen, Gonneke/0000-0003-3755-0236; Tan, Qihua/0000-0003-3194-0030; Pahlen, Shandell/0000-0003-0753-4155; Pedersen, Nancy/0000-0001-8057-3543; Haworth, Claire/0000-0002-8608-289X; Nistico, Lorenza/0000-0003-1805-6240; Skytthe, Axel/0000-0002-8629-4913; van Beijsterveldt, Toos/0000-0002-6617-4201; Rebato, Esther/0000-0003-1221-8501; Li, Lintao/0000-0002-0604-9660; Bartels, Meike/0000-0002-9667-7555; Silventoinen, Karri/0000-0003-1759-3079; Cunha Oliveira, Vinicius/0000-0002-8658-3774; Sund, Reijo/0000-0002-6268-8117; Sodemann, Morten/0000-0001-8992-2500; Rasmussen, Finn/0000-0001-7915-7809; Harden, Kathryn/0000-0002-1557-6737; Medda, Emanuela/0000-0003-4837-4549; Kyvik, Kirsten Ohm/0000-0003-2981-0245; Colodro Conde, Lucia/0000-0002-9004-364X WOS: 000517442200060 PubMed: 31364586 The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m(2)) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural-geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status. Academy of FinlandAcademy of Finland [266592, 100499, 205585, 118555, 141054, 265240, 263278, 264146]; Osaka University's International Joint Research Promotion Program; Centre of Research Excellence Grant from the National Health and Medical Research CouncilNational Health and Medical Research Council of Australia [1079102]; National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R01 HD068435, R01 MH062375, 1R01ESO15150-01, R21 AG039572]; National Medical Research Council Research Fellowship; California Tobacco-Related Disease Research ProgramUniversity of California System [7RT-0134H, 8RT-0107H, 6RT-0354H]; National Institute on AgingUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Aging (NIA) [1RO1-AG13662-01A2]; Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) [340-2013-5867]; Swedish Heart-Lung FoundationSwedish Heart-Lung Foundation; Swedish Asthma and Allergy Association's Research Foundation; Special Fund for Health Scientific Research in the Public Welfare, China [201502006]; NIDAUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Drug Abuse (NIDA) [DA011015, HD10333]; National Program for Research Infrastructure 2007 from the Danish Agency for Science, Technology and Innovation; Research Council for Health and Disease; Velux Foundation; US National Institute of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [P01 AG08761]; Fund of Scientific Research, FlandersFWO; ENGAGE - European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007 [201413]; National Institute of Alcohol Abuse and AlcoholismUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Alcohol Abuse & Alcoholism (NIAAA) [AA-12502, AA-00145, AA-09203]; Academy of Finland Center of Excellence in Complex Disease GeneticsAcademy of Finland [213506, 129680]; Cancer Research UKCancer Research UK [C1418/A7974]; W T Grant Foundation; University of London Central Research fund; Medical Research CouncilMedical Research Council UK (MRC) [G81/343, G120/635]; Economic and Social Research CouncilEconomic & Social Research Council (ESRC) [RES-000-22-2206]; Institute of Social Psychiatry [06/07-11]; Leverhulme Research FellowshipLeverhulme Trust [RF/2/RFG/2008/0145]; Goldsmiths, University of London; UK Medical Research CouncilMedical Research Council UK (MRC) [MR/M021475/1, G0901245]; National Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London; NIHUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R01AG053217, RC2 HL103416]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [81125007]; Global Research Network Program of the National Research Foundation [NRF 2011-220-E00006]; European Research Council (ERC)European Research Council (ERC) [240994]; Michigan State University; National Institute of Mental Health (NIMH)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01, 1R01-MH118848-01]; Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD) [R01-HD066040]; MSU Foundation [11-SPG-2518]; Fundacion Seneca, Regional Agency for Science and Technology, Murcia, Spain [08633/PHCS/08, 15302/PHCS/10, 19479/PI/14]; Ministry of Science and Innovation, SpainSpanish Government [PSI2009-11560, PSI2014-56680-R]; MagW/ZonMW [904-61-090, 985-10-002, 912-10-020, 904-61-193, 480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192]; European Research CouncilEuropean Research Council (ERC) [ERC-230374]; JSPS KAKENHI JP [23593419, 24792601, 26671010, 24590695, 26293128, 16K15385, 16K15978, 16K15989, 16H03261]; Australian National Health and Medical Research CouncilNational Health and Medical Research Council of Australia [437015, 607358]; Bonnie Babes Foundation [BBF20704]; Financial Markets Foundation for Children [032-2007]; Victorian Government; Portuguese agency for research (The Foundation for Science and Technology [FCT]) [POCI/DES/56834/2004]; Wellcome TrustWellcome Trust; Medical Research CouncilMedical Research Council UK (MRC); European UnionEuropean Union (EU); National Institute for Health Research (NIHR)National Institute for Health Research (NIHR); King's College London; Fonds Quebecois de la Recherche sur la Societe et la CultureFQRNT; Fonds de la Recherche en Sante du QuebecFonds de la Recherche en Sante du Quebec; Social Science and Humanities Research Council of Canada; National Health Research Development Program; Canadian Institutes for Health ResearchCanadian Institutes of Health Research (CIHR); Sainte-Justine Hospital's Research Center; Canada Research Chair ProgramCanada Research Chairs; National Research Foundation of KoreaNational Research Foundation of Korea [NRF-371-2011-1 B00047]; Swedish Research CouncilSwedish Research Council [2017-00641]; UK Biotechnology and Biological Sciences Research CouncilBiotechnology and Biological Sciences Research Council (BBSRC) [31/D19086]; MRCMedical Research Council UK (MRC) [MR/M021475/1]; Krkkale University [2009/43]; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114C117]; National Institute of Mental HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01 MH58354]; National Institute of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [NIA R01 AG018384, R01 AG018386, R01 AG022381, R01 AG022982]; VA San Diego Center of Excellence for Stress and Mental Health; Cooperative Studies Program of the Office of Research & Development of the United States Department of Veterans Affairs; Japan Society for the Promotion of ScienceMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science [15H05105]; Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust; Stockholm County Council (ALF-projects)Stockholm County Council; Twins, a nonprofit Association for Scientific Research in Multiple Births (Belgium); [5T32DA017637]; [5T32AG052371] This study was conducted within the CODATwins project (Academy of Finland #266592). K Silventoinen is supported by Osaka University's International Joint Research Promotion Program. This research was facilitated through access to Twins Research Australia, a national resource supported by a Centre of Research Excellence Grant (ID: 1079102), from the National Health and Medical Research Council. The Boston University Twin Project is funded by grants (#R01 HD068435 #R01 MH062375) from the National Institutes of Health to K. Saudino. Paulo Ferreira is funded by a National Medical Research Council Research Fellowship. California Twin Program was supported by The California Tobacco-Related Disease Research Program (7RT-0134H, 8RT-0107H, 6RT-0354H) and the National Institutes of Health (1R01ESO15150-01).; The Carolina African American Twin Study of Aging (CAATSA) was funded by a grant from the National Institute on Aging (grant 1RO1-AG13662-01A2) to K. E. Whitfield. The CATSS-Study is supported by the Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) framework grant no 340-2013-5867, grants provided by the Stockholm County Council (ALF-projects), the Swedish Heart-Lung Foundation and the Swedish Asthma and Allergy Association's Research Foundation.; Chinese National Twin Registry is funded by Special Fund for Health Scientific Research in the Public Welfare (Project No: 201502006), China. Colorado Twin Registry is funded by NIDA-funded center grant DA011015, & Longitudinal Twin Study HD10333; Author Huibregtse is supported by 5T32DA017637 and 5T32AG052371. Danish Twin Registry is supported by the National Program for Research Infrastructure 2007 from the Danish Agency for Science, Technology and Innovation, The Research Council for Health and Disease, the Velux Foundation and the US National Institute of Health (P01 AG08761). Since its origin, the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a nonprofit Association for Scientific Research in Multiple Births (Belgium). Data collection and analyses in Finnish twin cohorts have been supported by ENGAGE - European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement number 201413, National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145 and AA-09203 to R J Rose, the Academy of Finland Center of Excellence in Complex Disease Genetics (grant numbers: 213506, 129680), and the Academy of Finland (grants 100499, 205585, 118555, 141054, 265240, 263278 and 264146 to J Kaprio). Gemini was supported by a grant from Cancer Research UK (C1418/A7974). Waves 1-3 of Genesis 12-19 were funded by the W T Grant Foundation, the University of London Central Research fund and a Medical Research Council Training Fellowship (G81/343) and Career Development Award (G120/635) to Thalia C. Eley. Wave 4 was supported by grants from the Economic and Social Research Council (RES-000-22-2206) and the Institute of Social Psychiatry (06/07-11) to Alice M. Gregory, who was also supported at that time by a Leverhulme Research Fellowship (RF/2/RFG/2008/0145). Wave 5 was supported by funding to Alice M. Gregory from Goldsmiths, University of London. T. C. Eley is partly funded by a program grant from the UK Medical Research Council (MR/M021475/1).; This study presents independent research [partly] funded by the National Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health. The Minnesota Twin Registry (MTR) acknowledges support from NIH grant R01AG053217. Guangzhou Twin Eye Study is supported by National Natural Science Foundation of China (grant #81125007). Anthropometric measurements of the Hungarian twins were supported by Medexpert Ltd., Budapest, Hungary. Korean Twin-Family Register was supported by the Global Research Network Program of the National Research Foundation (NRF 2011-220-E00006). Longitudinal Israeli Study of Twins was funded by the Starting Grant no. 240994 from the European Research Council (ERC) to Ariel Knafo. The Michigan State University Twin Registry has been supported by Michigan State University, as well as grants R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01 and 1R01-MH118848-01 from the National Institute of Mental Health (NIMH), R01-HD066040 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD) and 11-SPG-2518 from the MSU Foundation. The content of this paper is solely the responsibility of the authors and does not necessarily represent the official views of the NIMH, the NICHD or the National Institutes of Health. The Murcia Twin Registry is supported by Fundacion Seneca, Regional Agency for Science and Technology, Murcia, Spain (08633/PHCS/08, 15302/PHCS/10 & 19479/PI/14) and Ministry of Science and Innovation, Spain (PSI2009-11560 & PSI2014-56680-R). The NAS-NRC Twin Registry acknowledges financial support from the National Institutes of Health grant number R21 AG039572. Netherlands Twin Register acknowledges the Netherlands Organization for Scientific Research (NWO) and MagW/ZonMW grants 904-61-090, 985-10-002, 912-10-020, 904-61-193,480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192; VU University's Institute for Health and Care Research (EMGO+); the European Research Council (ERC-230374), the Avera Institute, Sioux Falls, South Dakota (USA). Osaka University Aged Twin Registry is supported by grants from JSPS KAKENHI JP (23593419, 24792601, 26671010, 24590695, 26293128, 16K15385, 16K15978, 16K15989, 16H03261). PETS was supported by grants from the Australian National Health and Medical Research Council (grant numbers 437015 and 607358 to JC, and RS), the Bonnie Babes Foundation (grant number BBF20704 to JMC), the Financial Markets Foundation for Children (grant no. 032-2007 to JMC), and by the Victorian Government's Operational Infrastructure Support Program.; Madeira data comes from the following project: Genetic and environmental influences on physical activity, fitness and health: the Madeira family study Project reference: POCI/DES/56834/2004 Founded by the Portuguese agency for research (The Foundation for Science and Technology [FCT]). TwinsUK receives funding from the Wellcome Trust, Medical Research Council and European Union.; TwinsUK and M. Mangino are supported by the National Institute for Health Research (NIHR)-funded BioResource, Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust in partnership with King's College London. The Quebec Newborn Twin Study acknowledges financial support from the Fonds Quebecois de la Recherche sur la Societe et la Culture, the Fonds de la Recherche en Sante du Quebec, the Social Science and Humanities Research Council of Canada, the National Health Research Development Program, the Canadian Institutes for Health Research, Sainte-Justine Hospital's Research Center, and the Canada Research Chair Program (Michel Boivin). South Korea Twin Registry is supported by National Research Foundation of Korea (NRF-371-2011-1 B00047). We acknowledge The Swedish Twin Registry for access to data. The Swedish Twin Registry is managed by Karolinska Institutet and receives funding through the Swedish Research Council under the grant no. 2017-00641.; The Twins Early Development Study (TEDS) is supported by a program grant (G0901245) from the UK Medical Research Council and the work on obesity in TEDS is supported in part by a grant from the UK Biotechnology and Biological Sciences Research Council (31/D19086). Currently TEDS is supported by MRC grant 'MR/M021475/1'. The Texas Twin Project is currently funded by grant R01HD083613 from the National Institutes of Health. S. Y. oncel and F. Aliev are supported by Krkkale University Research Grant: KKU, 2009/43 and TUBITAK grant 114C117. The University of Southern California Twin Study is funded by a grant from the National Institute of Mental Health (R01 MH58354). Washington State Twin Registry (formerly the University of Washington Twin Registry) was supported in part by grant NIH RC2 HL103416 (D. Buchwald, PI). Vietnam Era Twin Study of Aging was supported by National Institute of Health grants NIA R01 AG018384, R01 AG018386, R01 AG022381 and R01 AG022982, and, in part, with resources of the VA San Diego Center of Excellence for Stress and Mental Health. The Cooperative Studies Program of the Office of Research & Development of the United States Department of Veterans Affairs has provided financial support for the development and maintenance of the Vietnam Era Twin (VET) Registry. The content of this paper is solely the responsibility of the authors and does not necessarily represent the official views of the NIA/NIH, or the VA. The West Japan Twins and Higher Order Multiple Births Registry was supported by Grant-in-Aid for Scientific Research (B) (grant number 15H05105) from the Japan Society for the Promotion of Science.

Objectives The aims of this study were to investigate perceived childcare burdens among mothers with an inter-pregnancy interval of less than 12 months, and to identify the factors associated with those perceptions.Methods Anonymous, self-administered questionnaires on inter-pregnancy intervals, the Edinburgh postnatal depression scale (EPDS), and the childcare emotion scale were distributed to mothers who visited one of three health and welfare centers in City A for three-month well-baby checkups. Six hundred eighty-five subjects were classified into four groups according to their inter-pregnancy interval (12 months apart; ≥12 months but24 months apart; ≥24 months apart; and a group with no siblings), and they was used to analyze associations between the timing of pregnancy and the mothers' perceptions of their childcare burdens. Chi-squared tests, a one-way analysis of variance, the Kruskal-Wallis test, and linear regression analyses were used for analysis.Results The inter-pregnancy interval was12 months in 35 of the 685 respondents, ≥12 months but24 months in 114 respondents, and ≥24 months in 194 respondents. There were 342 respondents in the no-siblings group. Linear regression analyses disclosed some factors associated with the subordinate items of the childcare emotion scale. "Feeling restricted by childcare duties" is significantly correlated to inter-pregnancy interval (P=.032), family composition (P=.014), time of sleeping (P=.010), and night wake-up time (P=.001). "Feeling of burden because of the child's attitude and behavior" was significantly related to inter-pregnancy interval (P.001), mother's age (P=.003), time of sleeping (P=.009), and night wake-up time (P=.002). "Anxiety about the child's growth" was significantly related to inter-pregnancy interval (P.001), mother's age (P=.016), and gestational age (P.001). In addition, the group with gestation intervals of less than 12 months had significantly higher numbers of women in single-parent households (P=.005), who were unmarried (P=.007), had only a junior high school education (P=.0027), and were 24 years old or younger (P.001).Conclusion The pregnancy interval is significantly related to the "Feeling restricted by childcare duties," "Feeling of burden because of the child's attitude and behavior," and "Anxiety about the child's growth," even after adjusting the influence of other factors. In addition, the results of this study demonstrated that mothers in the12 months group were more likely to be in a single-parent household, unmarried, with low educational attainment, and were 24 years old or younger. The results suggest that greater support is needed for these mothers.

The new West Japan Twins and Higher Order Multiple Births Registry was established by recruiting young twins and multiple births and by referrals from public health centers in the 1990s. The participants included in the survey comprised over 7800 twins and 4241 higher order multiples, and their families. Specifically, the present registry contains one of the largest triplet samples in the world. For these twins and multiples, data on year of delivery, mode of delivery, gestational age, intrapartum complications, longitudinal physical measures, motor milestones, cerebral palsy and feeding methods were obtained from records in the Maternal and Child Health Handbooks and schools. Participating mothers were asked to indicate family structure, parental educational history, maternal sleeping time, maternal health condition, maternal and paternal age at multiple delivery, complications during pregnancy, handedness of multiples and age at menarche of multiples. However, the zygosity differed among the various collaborating public health centers according to factors such as the time of investigation. Follow-up questionnaires have been mailed out every 3–4 years for longitudinal studies. This article describes the goals of this registry, recruitment of multiples and the focus of the study. The goals of this registry are not only to conduct research on human genetics and maternal and child health, but also to contribute to providing appropriate information for families with multiples.

Loos, Ruth J F/0000-0002-8532-5087; Kaprio, Jaakko/0000-0002-3716-2455; Huibregtse, Brooke M./0000-0003-0977-7249; de Freitas, Duarte Luis/0000-0001-6642-3370; Aliev, Fazil/0000-0001-8357-4699; Medda, Emanuela/0000-0003-4837-4549; Bartels, Meike/0000-0002-9667-7555; Latvala, Antti/0000-0001-5695-117X; Sund, Reijo/0000-0002-6268-8117; Rebato, Esther/0000-0003-1221-8501; Silventoinen, Karri/0000-0003-1759-3079; Aaltonen, Sari/0000-0002-2873-4263; Nistico, Lorenza/0000-0003-1805-6240; Knafo-Noam, Ariel/0000-0003-0613-1960; van Beijsterveldt, Toos/0000-0002-6617-4201; Harden, Kathryn/0000-0002-1557-6737; Willemsen, Gonneke/0000-0003-3755-0236; Pahlen, Shandell/0000-0003-0753-4155 WOS: 000465255700021 PubMed: 30950584 Objective The objective of this study was to analyze how parental education modifies the genetic and environmental variances of BMI from infancy to old age in three geographic-cultural regions. Methods A pooled sample of 29 cohorts including 143,499 twin individuals with information on parental education and BMI from age 1 to 79 years (299,201 BMI measures) was analyzed by genetic twin modeling. Results Until 4 years of age, parental education was not consistently associated with BMI. Thereafter, higher parental education level was associated with lower BMI in males and females. Total and additive genetic variances of BMI were smaller in the offspring of highly educated parents than in those whose parents had low education levels. Especially in North American and Australian children, environmental factors shared by co-twins also contributed to the higher BMI variation in the low education level category. In Europe and East Asia, the associations of parental education with mean BMI and BMI variance were weaker than in North America and Australia. Conclusions Lower parental education level is associated with higher mean BMI and larger genetic variance of BMI after early childhood, especially in the obesogenic macro-environment. The interplay among genetic predisposition, childhood social environment, and macro-social context is important for socioeconomic differences in BMI. Collaborative Project of Development of Anthropometrical Measures in Twins (Academy of Finland) [266592]; Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social and Medical Sciences Framework Grant [340-2013-5867]; Stockholm County Council (ALF projects)Stockholm County Council; Swedish Heart-Lung FoundationSwedish Heart-Lung Foundation; Swedish Asthma and Allergy Association's Research Foundation; Netherlands Organization for Scientific ResearchNetherlands Organization for Scientific Research (NWO); MagW/ZonMW [904-61-090, 985-10-002, 912-10-020, 904-61-193, 480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie-56-464-14192]; Vrije University's Institute for Health and Care Research; European Research Council (ERC)European Research Council (ERC) [230374]; Avera Institute, Sioux Falls, South Dakota; European Network for Genetic and Genomic Epidemiology (ENGAGE) [FP7-HEALTH-F4-2007, 201413]; National Institute of Alcohol Abuse and AlcoholismUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Alcohol Abuse & Alcoholism (NIAAA) [AA-12502, AA-00145, AA-09203]; Academy of Finland Center of Excellence in Complex Disease GeneticsAcademy of Finland [213506, 129680]; Academy of FinlandAcademy of Finland [100499, 205585, 118555, 141054, 265240, 264146, 312073]; Fund of Scientific Research, FlandersFWO; Twins, a nonprofit Association for Scientific Research in Multiple Births (Belgium); Cancer Research UKCancer Research UK [C1418/A7974]; European Union's Seventh Framework Programmes ENGAGE Consortium [HEALTH-F4-2007-201413]; Biobank Standardization and Harmonization for Research Excellence in the European Union [HEALTH-F4-2010-261433]; Kirikkale UniversityKirikkale University [2009/43]; Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114C117]; Osaka University's International Joint Research Promotion Program; National Institutes of Health (NIH)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R01HD068435, R01MH062375]; California Tobacco-Related Disease Research ProgramUniversity of California System [7RT-0134H, 8RT-0107H, 6RT-0354H]; NIHUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [1R01ESO15150-01, AA023322, HD081437, R21AG039572]; National Institute on Aging (NIA)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Aging (NIA) [1R01AG13662-01A2]; National Institute on Drug AbuseUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Drug Abuse (NIDA) [DA011015]; Longitudinal Twin Study grant [HD10333]; MSU; National Institute of Mental Health (NIMH)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01MH081813, R01MH0820-54, R01MH092377-02, R21MH070542-01, R03MH63851-01]; Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD) [R01HD066040]; MSU Foundation [11-SPG-2518]; NIMHUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01MH58354]; NIH/NIAUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Aging (NIA) [R01AG018384, R01AG018386, R01AG022381, R01AG022982]; VA San Diego Center of Excellence for Stress and Mental Health; Cooperative Studies Program of the Office of Research & Development of the US Department of Veterans Affairs (VA); Global Research Network Program of the National Research Foundation (NRF) [2011-220-E00006]; NRF of Korea [NRF-371-2011-1 B00047]; Japan Society for the Promotion of ScienceMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science [15H05105]; National Health and Medical Research CouncilNational Health and Medical Research Council of Australia [1079102]; ERCEuropean Research Council (ERC) [240994]; [POCI/DES/56834/2004]; [5T32DA017637]; [5T32AG052371] This study was conducted within the Collaborative Project of Development of Anthropometrical Measures in Twins (Academy of Finland Grant 266592). Funding for individual collaborators is as follows. The Child and Adolescent Twin Study in Sweden is supported by the Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social and Medical Sciences Framework Grant 340-2013-5867, grants provided by the Stockholm County Council (ALF projects), the Swedish Heart-Lung Foundation, and the Swedish Asthma and Allergy Association's Research Foundation. The Netherlands Twin Register acknowledges support from the Netherlands Organization for Scientific Research and MagW/ZonMW Grants 904-61-090, 985-10-002, 912-10-020, 904-61-193,480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, and Spinozapremie-56-464-14192; Vrije University's Institute for Health and Care Research; the European Research Council (ERC; grant 230374); and the Avera Institute, Sioux Falls, South Dakota. Data collection and analyses in Finnish twin cohorts have been supported by the European Network for Genetic and Genomic Epidemiology (ENGAGE; FP7-HEALTH-F4-2007, grant agreement 201413), the National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145, and AA-09203 to R. J. Rose), the Academy of Finland Center of Excellence in Complex Disease Genetics (grants 213506 and 129680), and the Academy of Finland (grants 100499, 205585, 118555, 141054, 265240, 264146, and 312073 to J. Kaprio). Since its origin, the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a nonprofit Association for Scientific Research in Multiple Births (Belgium). Gemini was supported by a grant from Cancer Research UK (C1418/A7974). Data collection and research stemming from the Norwegian Twin Registry are supported, in part, by the European Union's Seventh Framework Programmes ENGAGE Consortium (grant agreement HEALTH-F4-2007-201413) and Biobank Standardization and Harmonization for Research Excellence in the European Union (grant agreement HEALTH-F4-2010-261433). Madeira data come from Genetic and Environmental Influences on Physical Activity, Fitness and Health: the Madeira Family Study (project reference: POCI/DES/56834/2004, founded by the Portuguese agency for research [the Foundation for Science and Technology]). S. Y. Oncel and F. Aliev are supported by a Kirikkale University research grant (2009/43) and a Scientific and Technological Research Council of Turkey grant (114C117). K. Silventoinen is supported by Osaka University's International Joint Research Promotion Program. The Boston University Twin Project is funded by grants (R01HD068435 and R01MH062375) from the National Institutes of Health (NIH) to K. J. Saudino. The California Twin Program was supported by the California Tobacco-Related Disease Research Program (7RT-0134H, 8RT-0107H, and 6RT-0354H) and NIH (1R01ESO15150-01). The Carolina African American Twin Study of Aging was funded by a grant from the National Institute on Aging (NIA; 1R01AG13662-01A2) to K. E. Whitfield. The Colorado Twin Registry is funded by National Institute on Drug Abuse grant DA011015 and Longitudinal Twin Study grant HD10333; B. M. Huibregtse is supported by 5T32DA017637 and 5T32AG052371.; The Michigan State University (MSU) Twin Registry has been supported by MSU, as well as by grants R01MH081813, R01MH0820-54, R01MH092377-02, R21MH070542-01, and R03MH63851-01 from the National Institute of Mental Health (NIMH), grant R01HD066040 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), and grant 11-SPG-2518 from the MSU Foundation. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of NIMH, NICHD, or NIH. The University of Southern California Twin Study is funded by a grant from NIMH (R01MH58354). The Texas Twin Project is currently funded by grants AA023322 and HD081437 from NIH. The Vietnam Era Twin Study of Aging was supported by NIH/NIA grants R01AG018384, R01AG018386, R01AG022381, and R01AG022982 and, in part, with resources of the VA San Diego Center of Excellence for Stress and Mental Health. The Cooperative Studies Program of the Office of Research & Development of the US Department of Veterans Affairs (VA) has provided financial support for the development and maintenance of the Vietnam Era Twin Registry. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of NIA/NIH or VA. The National Academy of Sciences-National Research Council Twin Registry acknowledges financial support from NIH grant R21AG039572. The Korean TwinFamily Register was supported by the Global Research Network Program of the National Research Foundation (NRF; 2011-220-E00006). The South Korea Twin Registry is supported by the NRF of Korea (NRF-371-2011-1 B00047). The West Japan Twins and Higher Order Multiple Births Registry was supported by a Grant-inAid for Scientific Research (B) (15H05105) from the Japan Society for the Promotion of Science. This research was facilitated through access to Twins Research Australia, a national resource supported by a Centre of Research Excellence Grant (1079102) from the National Health and Medical Research Council. The Longitudinal Israeli Study of Twins was funded by Starting Grant 240994 from the ERC to A. Knafo-Noam.

BackgroundThere is evidence that birth weight is positively associated with education, but it remains unclear whether this association is explained by familial environmental factors, genetic factors or the intrauterine environment. We analysed the association between birth weight and educational years within twin pairs, which controls for genetic factors and the environment shared between co-twins.MethodsThe data were derived from nine twin cohorts in eight countries including 6116 complete twin pairs. The association between birth weight and educational attainment was analysed both between individuals and within pairs using linear regression analyses.ResultsIn between-individual analyses, birth weight was not associated with educational years. Within-pairs analyses revealed positive but modest associations for some sex, zygosity and birth year groups. The greatest association was found in dizygotic (DZ) men (0.65 educational years/kg birth weight, p=0.006); smaller effects of 0.3 educational years/kg birth weight were found within monozygotic (MZ) twins of both sexes and opposite-sex DZ twins. The magnitude of the associations differed by birth year in MZ women and opposite-sex DZ twins, showing a positive association in the 1915–1959 birth cohort but no association in the 1960–1984 birth cohort.ConclusionAlthough associations are weak and somewhat inconsistent, our results suggest that intrauterine environment may play a role when explaining the association between birth weight and educational attainment.

Background: Maternal well-being is an important issue not only for mothers but also for their offspring and whole families. This study aims to clarify differences in subjective well-being for mothers with infants and associated factors by comparing Japanese and Finnish mothers. Methods: In Finland, 101 mothers with infants who received health check-ups at child's age 4 months participated in the study. In Japan, 505 mothers with infants who should receive health check-ups at child's age 4 months and, whose age, age of the infant and number of children matched with the Finnish mothers were selected. The factors associated with maternal subjective well-being were explored by the linear regression analysis. All Finnish mothers had individual infant health check-ups by nurses in Child Health Clinics nearly monthly. The same nurse was responsible for following up the family throughout the years. All Japanese participants received group health check-up once at child's age 3 to 4 months, and a nurse did not cover same child and their mother. Results: Finnish mothers showed significantly better subjective well-being compared with Japanese mothers. Whereas 85% of Finnish mothers responded that they had obtained childcare information from public health nurses, significantly fewer Japanese mothers indicated the same response (8%). Linear regression analyses disclosed that mothers' subjective well-being was associated with country, mothers' stress and age. Conclusion: Finnish mothers had better subjective well-being than Japanese mothers. Our results may indicate that the Finnish health care system supports mothers better than the Japanese health care system does.

Background: The genetic architecture of birth size may differ geographically and over time. We examined differences in the genetic and environmental contributions to birth weight, length, and ponderal index (PI) across geographic-cultural regions (Europe, North-America and Australia, and East-Asia) and across birth cohorts and how gestational age modifies these effects.Methods: Data from 26 twin cohorts in 16 countries including 57613 monozygotic and dizygotic twin pairs were pooled. Genetic and environmental variations of birth size were estimated using genetic structural equation modeling.Results: The variance of birth weight and length was predominantly explained by shared environmental factors, whereas the variance of PI was explained both by shared and unique environmental factors. Genetic variance contributing to birth size was small. Adjusting for gestational age decreased the proportions of shared environmental variance and increased the propositions of unique environmental variance. Genetic variance was similar in the geographic-cultural regions, but shared environmental variance was smaller in East-Asia than in Europe and North-America and Australia. The total variance and shared environmental variance of birth length and PI were greater from the birth cohort 1990-1999 onwards compared with the birth cohorts from 1970-1979 to 1980-1989.Conclusion: The contribution of genetic factors to birth size is smaller than that of shared environmental factors, which is partly explained by gestational age. Shared environmental variances of birth length and PI were greater in the latest birth cohorts and differed also across geographic-cultural regions. Shared environmental factors are important when explaining differences in the variation of birth size globally and over time.

The mechanisms behind handedness formation in humans are still poorly understood. Very low birthweight is associated with higher odds of left-handedness, but whether this is due to low birthweight itself or premature birth is unknown. Handedness has also been linked to development, but the role of birthweight behind this association is unclear. Knowing that birthweight is lower in multiple births, triplets being about 1.5 kg lighter in comparison with singletons, and that multiples have a higher prevalence of left-handedness than singletons, we studied the association between birthweight and handedness in two large samples consisting exclusively of triplets from Japan (n = 1,305) and the Netherlands (n = 947). In both samples, left-handers had significantly lower birthweight (Japanese mean = 1,599 g [95% confidence interval (CI): 1,526–1,672 g]; Dutch mean = 1,794 g [95% CI: 1,709–1,879 g]) compared with right-handers (Japanese mean = 1,727 g [95% CI: 1,699–1,755 g]; Dutch mean = 1,903 g [95% CI: 1,867–1,938 g]). Within-family and between-family analyses both suggested that left-handedness is associated with lower birthweight, also when fully controlling for gestational age. Left-handers also had significantly delayed motor development and smaller infant head circumference compared with right-handers, but these associations diluted and became nonsignificant when controlling for birthweight. Our study in triplets provides evidence for the link between low birthweight and left-handedness. Our results also suggest that developmental differences between left- and right-handers are due to a shared etiology associated with low birthweight.

It is well established that boys are born heavier and longer than girls, but it remains unclear whether birth size in twins is affected by the sex of their co-twin. We conducted an individual-based pooled analysis of 21 twin cohorts in 15 countries derived from the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins), including 67,850 dizygotic twin individuals. Linear regression analyses showed that boys having a co-twin sister were, on average, 31 g (95%Cl 18 to 45) heavier and 0.16 cm (95%CI 0.045 to 0.274) longer than those with a co-twin brother. In girls, birth size was not associated (5 g birth weight; 95%Cl -8 to -18 and -0.089 cm birth length; 95% CI -0.202 to 0.025) with the sex of the co-twin. Gestational age was slightly shorter in boy-boy pairs than in boy-girl and girl-girl pairs. When birth size was standardized by gestational age, the magnitude of the associations was attenuated in boys, particularly for birth weight. In conclusion, boys with a co-twin sister are heavier and longer at birth than those with a co-twin brother. However, these differences are modest and partly explained by a longer gestation in the presence of a co-twin sister. This study was conducted within the CODATwins project (Academy of Finland #266592). The Australian Twin Registry is supported by a Centre of Research Excellence (grant ID 1079102) from the National Health and Medical Research Council administered by the University of Melbourne. The Carolina African American Twin Study of Aging (CAATSA) was funded by a grant from the National Institute on Aging (grant 1RO1-AG13662-01A2) to K.E. Whitfield. The CATSS-Study is supported by the Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) framework grant no 340-2013-5867, grants provided by the Stockholm County Council (ALF-projects), the Swedish Heart-Lung Foundation and the Swedish Asthma and Allergy Association's Research Foundation. Since its origin the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a non-profit Association for Scientific Research in Multiple Births (Belgium). Data collection and analyses in Finnish twin cohorts have been supported by ENGAGE-European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement number 201413, National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145, and AA-09203 to R J Rose, the Academy of Finland Center of Excellence in Complex Disease Genetics (grant numbers: 213506, 129680), and the Academy of Finland (grants 100499, 205585, 118555, 141054, 265240, 263278 and 264146 to J Kaprio). Gemini was supported by a grant from Cancer Research UK (C1418/A7974). Anthropometric measurements of the Hungarian twins were supported by Medexpert Ltd., Budapest, Hungary. Longitudinal Israeli Study of Twins was funded by the Starting Grant no. 240994 from the European Research Council (ERC) to Ariel Knafo. The Michigan State University Twin Registry has been supported by Michigan State University, as well as grants R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01 from the National Institute of Mental Health (NIMH), R01-HD066040 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD), and 11-SPG-2518 from the MSU Foundation. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the NIMH, the NICHD, or the National Institutes of Health. PETS was supported by grants from the Australian National Health and Medical Research Council (grant numbers 437015 and 607358 to JC, and RS), the Bonnie Babes Foundation (grant number BBF20704 to JMC), the Financial Markets Foundation for Children (grant no. 032-2007 to JMC), and by the Victorian Government's Operational Infrastructure Support Program. The Quebec Newborn Twin Study acknowledges financial support from the Fonds Quebecois de la Recherche sur la Societe et la Culture, the Fonds de la Recherche en Sante du Quebec, the Social Science and Humanities Research Council of Canada, the National Health Research Development Program, the Canadian Institutes for Health Research, Sainte-Justine Hospital's Research Center, and the Canada Research Chair Program (Michel Boivin). The Twins Early Development Study (TEDS) is supported by a program grant (G0901245) from the UK Medical Research Council and the work on obesity in TEDS is supported in part by a grant from the UK Biotechnology and Biological Sciences Research Council (31/D19086). Currently TEDS is supported by MRC grant 'MR/M021475/1'. The West Japan Twins and Higher Order Multiple Births Registry was supported by Grant-in-Aid for Scientific Research (B) (grant number 15H05105) from the Japan Society for the Promotion of Science. Netherlands Twin Register acknowledges the Netherlands Organization for Scientific Research (NWO) and MagW/ZonMW grants 904-61-090, 985-10-002, 912-10-020, 904-61-193,480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192; VU University's Institute for Health and Care Research (EMGO+); the European Research Council (ERC - 230374), the Avera Institute, Sioux Falls, South Dakota (USA).

Kandler, Christian/0000-0002-9175-235X; Bartels, Meike/0000-0002-9667-7555; Medland, Sarah E/0000-0003-1382-380X; Kaprio, Jaakko/0000-0002-3716-2455; Fagnani, Corrado/0000-0001-5771-7772; de Freitas, Duarte Luis/0000-0001-6642-3370; Hjelmborg, Jacob/0000-0001-9630-9149; mangino, massimo/0000-0002-2167-7470; Busjahn, Andreas/0000-0001-9650-6919; Montgomery, Grant W/0000-0002-4140-8139; Moller, Soren/0000-0003-0858-4269; Heikkila, Kauko/0000-0002-9256-8028; Skytthe, Axel E/0000-0002-8629-4913; Christensen, Kaare/0000-0002-5429-5292; Knafo-Noam, Ariel/0000-0003-0613-1960; ONCEL, Sevgi YURT/0000-0002-0990-292X; Sund, Reijo/0000-0002-6268-8117; Aliev, Fazil/0000-0001-8357-4699; Magnusson, Patrik/0000-0002-7315-7899; Huibregtse, Brooke M./0000-0003-0977-7249; Loos, Ruth J F/0000-0002-8532-5087; Boivin, Michel/0000-0001-8621-9844; Kyvik, Kirsten Ohm/0000-0003-2981-0245; Pahlen, Shandell/0000-0003-0753-4155; van Beijsterveldt, Toos/0000-0002-6617-4201; McAdams, Tom/0000-0002-6825-3499; Sodemann, Morten/0000-0001-8992-2500; Pedersen, Nancy/0000-0001-8057-3543; Derom, Catherine/0000-0001-5574-796X; Plomin, Robert/0000-0002-0756-3629; Rebato, Esther/0000-0003-1221-8501; Saffery, Richard/0000-0002-9510-4181; Harden, Kathryn/0000-0002-1557-6737; Willemsen, Gonneke/0000-0003-3755-0236; Aaltonen, Sari/0000-0002-2873-4263; Silventoinen, Karri/0000-0003-1759-3079; Rasmussen, Finn/0000-0001-7915-7809; Haworth, Claire/0000-0002-8608-289X; Llewellyn, Clare/0000-0002-0066-2827 WOS: 000381870200017 PubMed: 27413137 Background: Both genetic and environmental factors are known to affect body mass index (BMI), but detailed understanding of how their effects differ during childhood and adolescence is lacking. Objectives: We analyzed the genetic and environmental contributions to BMI variation from infancy to early adulthood and the ways they differ by sex and geographic regions representing high (North America and Australia), moderate (Europe), and low levels (East Asia) of obesogenic environments. Design: Data were available for 87,782 complete twin pairs from 0.5 to 19.5 y of age from 45 cohorts. Analyses were based on 383,092 BMI measurements. Variation in BMI was decomposed into genetic and environmental components through genetic structural equation modeling. Results: The variance of BMI increased from 5 y of age along with increasing mean BMI. The proportion of BMI variation explained by additive genetic factors was lowest at 4 y of age in boys (a(2) = 0.42) and girls (a(2) = 0.41) and then generally increased to 0.75 in both sexes at 19 y of age. This was because of a stronger influence of environmental factors shared by co-twins in midchildhood. After 15 y of age, the effect of shared environment was not observed. The sex-specific expression of genetic factors was seen in infancy but was most prominent at 13 y of age and older. The variance of BMI was highest in North America and Australia and lowest in East Asia, but the relative proportion of genetic variation to total variation remained roughly similar across different regions. Conclusions: Environmental factors shared by co-twins affect BMI in childhood, but little evidence for their contribution was found in late adolescence. Our results suggest that genetic factors play a major role in the variation of BMI in adolescence among populations of different ethnicities exposed to different environmental factors related to obesity. CODATwins project (Academy of Finland) [266592]; NIHUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R01 HD068435, R01 MH062375, 1R01ESO15150-01, HD081437, AA023322, RC2 HL103416]; California Tobacco-Related Disease Research ProgramUniversity of California System [7RT-0134H, 8RT-0107H, 6RT-0354H]; Special Fund for Health Scientific Research in the Public Welfare, China [201502006]; NIDAUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Drug Abuse (NIDA) [DA011015, HD10333]; National Program for Research Infrastructure from the Danish Agency for Science, Technology and Innovation, The Research Council for Health and Disease; Velux Foundation; US NIH grantUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [P01 AG08761]; Fund of Scientific Research, Flanders and Twins, a nonprofit Association for Scientific Research in Multiple Births (Belgium); ENGAGE-European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4 [201413]; National Institute of Alcohol Abuse and AlcoholismUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Alcohol Abuse & Alcoholism (NIAAA) [AA-12502, AA-00145, AA-09203]; Academy of Finland Center of Excellence in Complex Disease Genetics grantAcademy of Finland [213506, 129680]; Academy of Finland grantAcademy of Finland [100499, 205585, 118555, 141054, 265240, 263278, 264146]; Osaka University's International Joint Research Promotion Program; Cancer Research UKCancer Research UK [C1418/A7974]; W T Grant Foundation; University of London Central Research fund; Medical Research CouncilMedical Research Council UK (MRC) [G81/343, G120/635]; Economic and Social Research CouncilEconomic & Social Research Council (ESRC) [RES-000-22-2206]; Institute of Social Psychiatry [06/07-11]; Leverhulme Research Fellowship grant [RF/2/RFG/2008/0145]; Goldsmiths, University of London, United Kingdom; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [81125007]; Medexpert Ltd., Budapest, Hungary; European Research CouncilEuropean Research Council (ERC) [240994, 230374]; Michigan State University; National Institute of Mental HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01]; Eunice Kennedy Shriver National Institute for Child Health and Human DevelopmentUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD) [R01-HD066040]; MSU Foundation [11-SPG-2518]; NIH grantUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R21 AG039572]; MagW/ZonMW grant [904-61-090, 985-10-002, 912-10-020, 904-61-193, 480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464- 14192]; VU University's Institute for Health and Care Research; Avera Institute, Sioux Falls, SD; Australian National Health and Medical Research Council grantNational Health and Medical Research Council of Australia [437015, 607358]; Bonnie Babes Foundation [BBF20704]; Financial Markets Foundation for Children grant [032-2007]; Victorian Government's Operational Infrastructure Support Program; Portuguese agency for research (The Foundation for Science and Technology) [POCI/DES/56834/2004]; Fonds Quebecois de la Recherche sur la Societe et la CultureFQRNT; Fonds de la Recherche en Sante du QuebecFonds de la Recherche en Sante du Quebec; Social Science and Humanities Research Council of Canada; National Health Research Development Program; Canadian Institutes for Health ResearchCanadian Institutes of Health Research (CIHR); Sainte-Justine Hospital's Research Center; Canada Research Chair ProgramCanada Research Chairs; National Research Foundation of KoreaNational Research Foundation of Korea [NRF-371-2011-1 B00047]; UK Medical Research CouncilMedical Research Council UK (MRC) [G0901245]; UK Biotechnology and Biological Sciences Research Council grant [31/D19086]; Kirikkale University Research grantKirikkale University [KKU 2009/43]; TUBITAK grantTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114C117]; European CommunityEuropean Community (EC); National Institute for Health Research BioResource Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London, United Kingdom; National Institute of Mental Health grantUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01 MH58354]; Japan Society for the Promotion of ScienceMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science [15H05105]; [5T32DA017637-11]; Medical Research CouncilMedical Research Council UK (MRC) [G0901245]; NNF Center for Basic Metabolic ResearchNovo Nordisk Foundation [Metabolic Genetics]; Novo Nordisk FondenNovo NordiskNovo Nordisk Foundation [NNF10CC1016515] This study was conducted within the CODATwins project (Academy of Finland #266592). Support for participating twin projects: The Boston University Twin Project is funded by grants R01 HD068435 and R01 MH062375 from the NIH to KS. California Twin Program was supported by The California Tobacco-Related Disease Research Program grants 7RT-0134H, 8RT-0107H, and 6RT-0354H and by NIH grant 1R01ESO15150-01. Chinese National Twin Registry is funded by Special Fund for Health Scientific Research in the Public Welfare (Project No: 201502006), China. Colorado Twin Registry is funded by NIDA funded center grant DA011015, and Longitudinal Twin Study HD10333; BMH is supported by to 5T32DA017637-11. Danish Twin Registry is supported by the National Program for Research Infrastructure 2007 from the Danish Agency for Science, Technology and Innovation, The Research Council for Health and Disease, the Velux Foundation and the US NIH grant P01 AG08761. Since its origin the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a nonprofit Association for Scientific Research in Multiple Births (Belgium). Data collection and analyses in Finnish twin cohorts have been supported by ENGAGE-European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement 201413; National Institute of Alcohol Abuse and Alcoholism grants AA-12502, AA-00145, and AA-09203 to RJR; the Academy of Finland Center of Excellence in Complex Disease Genetics grants 213506 and 129680; and the Academy of Finland grants 100499, 205585, 118555, 141054, 265240, 263278, and 264146 to JK. KS is supported by Osaka University's International Joint Research Promotion Program. Gemini was supported by a grant from Cancer Research UK (C1418/A7974). Waves 1-3 of Genesis 12-19 were funded by the W T Grant Foundation, the University of London Central Research fund and Medical Research Council Training Fellowship grant G81/343 and Career Development Award G120/635 to TCE. Wave 4 was supported by the Economic and Social Research Council grant RES-000-22-2206 and the Institute of Social Psychiatry (06/07-11) to AMG, who was also supported at that time by a Leverhulme Research Fellowship grant RF/2/RFG/2008/0145. Wave 5 was supported by funding to AMG from Goldsmiths, University of London, United Kingdom. Guangzhou Twin Eye Study is supported by National Natural Science Foundation of China grant 81125007. Anthropometric measurements of the Hungarian twins were supported by Medexpert Ltd., Budapest, Hungary. Longitudinal Israeli Study of Twins was funded by the Starting Grant 240994 from the European Research Council to AK. The Michigan State University Twin Registry has been supported by Michigan State University, as well as grants R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, and R03-MH63851-01 from the National Institute of Mental Health, R01-HD066040 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development, and 11-SPG-2518 from the MSU Foundation. The NAS-NRC Twin Registry acknowledges financial support from NIH grant R21 AG039572. Netherlands Twin Register acknowledges the Netherlands Organization for Scientific Research and MagW/ZonMW grants 904-61-090, 985-10-002, 912-10-020, 904-61-193,480-04-004, 463-06-001, 451-04-034, and 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464- 14192; VU University's Institute for Health and Care Research; the European Research Council grant 230374; and the Avera Institute, Sioux Falls, SD.; PETS was supported by the Australian National Health and Medical Research Council grant 437015 and 607358 to JC and RS, the Bonnie Babes Foundation grant BBF20704 to JMC, the Financial Markets Foundation for Children grant 032-2007 to JMC, and by the Victorian Government's Operational Infrastructure Support Program. Madeira data comes from the following project: Genetic and environmental influences on physical activity, fitness and health: the Madeira family study Project reference: POCI/DES/56834/2004 Founded by the Portuguese agency for research (The Foundation for Science and Technology). The Quebec Newborn Twin Study acknowledges financial support from the Fonds Quebecois de la Recherche sur la Societe et la Culture, the Fonds de la Recherche en Sante du Quebec, the Social Science and Humanities Research Council of Canada, the National Health Research Development Program, the Canadian Institutes for Health Research, Sainte-Justine Hospital's Research Center, and the Canada Research Chair Program (MB). South Korea Twin Registry is supported by National Research Foundation of Korea grant NRF-371-2011-1 B00047. The Texas Twin Project is currently funded by grants AA023322 and HD081437 from the NIH. The Twins Early Development Study is supported by program grant G0901245 from the UK Medical Research Council and the work on obesity in the Twins Early Development Study is supported in part by the UK Biotechnology and Biological Sciences Research Council grant 31/D19086. SYO and FA are supported by Kirikkale University Research grant KKU 2009/43 and TUBITAK grant 114C117. TwinsUK was funded by European Community's Seventh Framework Programme grant FP7/2007-2013. The study also receives support from the National Institute for Health Research BioResource Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London, United Kingdom. The University of Southern California Twin Study is funded by the National Institute of Mental Health grant R01 MH58354. University of Washington Twin Registry was supported in part by grant NIH RC2 HL103416 (D and PI). The West Japan Twins and Higher Order Multiple Births Registry was supported by Grant-in-Aid for Scientific Research (B) grant 15H05105 from the Japan Society for the Promotion of Science.

Background: There is evidence that birth size is positively associated with height in later life, but it remains unclear whether this is explained by genetic factors or the intrauterine environment. Aim: To analyze the associations of birth weight, length and ponderal index with height from infancy through adulthood within mono- and dizygotic twin pairs, which provides insights into the role of genetic and environmental individual-specific factors. Methods: This study is based on the data from 28 twin cohorts in 17 countries. The pooled data included 41,852 complete twin pairs (55% monozygotic and 45% same-sex dizygotic) with information on birth weight and a total of 112,409 paired height measurements at ages ranging from 1 to 69 years. Birth length was available for 19,881 complete twin pairs, with a total of 72,692 paired height measurements. The association between birth size and later height was analyzed at both the individual and within-pair level by linear regression analyses. Results: Within twin pairs, regression coefficients showed that a 1-kg increase in birth weight and a 1-cm increase in birth length were associated with 1.14-4.25 cm and 0.18-0.90 cm taller height, respectively. The magnitude of the associations was generally greater within dizygotic than within monozygotic twin pairs, and this difference between zygosities was more pronounced for birth length. Conclusion: Both genetic and individual-specific environmental factors play a role in the association between birth size and later height from infancy to adulthood, with a larger role for genetics in the association with birth length than with birth weight. This work was supported by the Academy of Finland (grant number #266592). The Australian Twin Registry is supported by a Centre of Research Excellence (grant ID 1079102) from the National Health and Medical Research Council administered by the University of Melbourne. The Boston University Twin Project is funded by grants (#R01 HD068435 #R01 MH062375) from the National Institutes of Health to K. Saudino. The Carolina African American Twin Study of Aging (CAATSA) was funded by a grant from the National Institute on Aging (grant 1RO1-AG13662-01A2) to K. E. Whitfield. The CATSS-Study is supported by the Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) framework grant no 340-2013-5867, grants provided by the Stockholm County Council (ALF-projects), the Swedish Heart-Lung Foundation and the Swedish Asthma and Allergy Association's Research Foundation. Colorado Twin Registry is funded by NIDA funded center grant DA011015, & Longitudinal Twin Study HD10333; Author Huibregtse is supported by 5T32DA017637 and 5T32AG052371. Since its origin the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a non-profit Association for Scientific Research in Multiple Births (Belgium). Data collection and analyses in Finnish twin cohorts have been supported by ENGAGE - European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement number 201413, National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145, and AA-09203 to R J Rose, the Academy of Finland Center of Excellence in Complex Disease Genetics (grant numbers: 213506, 129680), Centre of Excellence in Research on Mitochondria, Metabolism and Disease (FinMIT, grant 272376), the Academy of Finland (grants 100499, 205585, 118555, 141054, 265240, 263278 and 264146 to J Kaprio and grant 266286 and 314383 to K Pietilainen), the Finnish Diabetes Research Foundation, Novo Nordisk Foundation, Helsinki University Central Hospital and University of Helsinki. K Silventoinen is supported by Osaka University's International Joint Research Promotion Program. Gemini was supported by a grant from Cancer Research UK (C1418/A7974). Anthropometric measurements of the Hungarian twins were supported by Medexpert Ltd., Budapest, Hungary. Korean Twin-Family Register was supported by the Global Research Network Program of the National Research Foundation (NRF 2011-220-E00006). Longitudinal Israeli Study of Twins was funded by the Starting Grant no. 240994 from the European Research Council (ERC) to Ariel Knafo. The Michigan State University Twin Registry has been supported by Michigan State University, as well as grants R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01 from the National Institute of Mental Health (NIMH), R01-HD066040 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD), and 11-SPG-2518 from the MSU Foundation. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the NIMH, the NICHD, or the National Institutes of Health. PETS was supported by grants from the Australian National Health and Medical Research Council (grant numbers 437015 and 607358 to JC, and RS), the Bonnie Babes Foundation (grant number BBF20704 to JMC), the Financial Markets Foundation for Children (grant no. r 032-2007 to JMC), and by the Victorian Governments Operational Infrastructure Support Program. The Quebec Newborn Twin Study acknowledges financial support from the Fonds Quebecois de la Recherche sur la Societe et la Culture, the Fonds de la Recherche en Sante du Quebec, the Social Science and Humanities Research Council of Canada, the National Health Research Development Program, the Canadian Institutes for Health Research, Sainte-Justine Hospital's Research Center, and the Canada Research Chair Program (Michel Boivin). The Twins Early Development Study (TEDS) is supported by a program grant (MR/M021475/1) from the UK Medical Research Council and the work on obesity in TEDS is supported in part by a grant from the UK Biotechnology and Biological Sciences Research Council (31/D19086). The West Japan Twins and Higher Order Multiple Births Registry was supported by Grant-in-Aid for Scientific Research (B) (grant number 15H05105) from the Japan Society for the Promotion of Science. Netherlands Twin Register acknowledges the Netherlands Organization for Scientific Research (NWO) and MagW/ZonMW grants 904-61-090, 985-10-002, 912-10-020, 904-61-193, 480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192; VU University's Institute for Health and Care Research (EMGO +); the European Research Council (ERC - 230374), the Avera Institute, Sioux Falls, South Dakota (USA).

Kaprio, Jaakko/0000-0002-3716-2455; Knafo-Noam, Ariel/0000-0003-0613-1960; de Freitas, Duarte Luis/0000-0001-6642-3370; Haworth, Claire/0000-0002-8608-289X; Siribaddana, Sisira/0000-0001-5821-2557; Kyvik, Kirsten O/0000-0003-2981-0245; Aliev, Fazil/0000-0001-8357-4699; Craig, Jeffrey M/0000-0003-3979-7849; Ordonana, Juan R./0000-0001-7779-6017; Sund, Reijo/0000-0002-6268-8117; Bartels, Meike/0000-0002-9667-7555; Kandler, Christian/0000-0002-9175-235X; Fagnani, Corrado/0000-0001-5771-7772; Huibregtse, Brooke M./0000-0003-0977-7249; Montgomery, Grant W/0000-0002-4140-8139; Colodro-Conde, Lucia/0000-0002-9004-364X; Loos, Ruth J F/0000-0002-8532-5087; Busjahn, Andreas/0000-0001-9650-6919; ONCEL, Sevgi YURT/0000-0002-0990-292X; Christensen, Kaare/0000-0002-5429-5292; Martin, Nicholas/0000-0003-4069-8020; Tan, Qihua/0000-0003-3194-0030; ROMERA, JUAN FRANCISCO SANCHEZ/0000-0002-5405-6216; D'Ippolito, Cristina/0000-0001-7902-9380; Skytthe, Axel E/0000-0002-8629-4913; Tan, Qihua/0000-0003-3194-0030; Heikkila, Kauko/0000-0002-9256-8028; Duncan, Glen/0000-0001-6909-1869; Jelenkovic, Aline/0000-0002-6191-8371; Magnusson, Patrik/0000-0002-7315-7899; mangino, massimo/0000-0002-2167-7470; Medland, Sarah E/0000-0003-1382-380X; Saffery, Richard/0000-0002-9510-4181; Plomin, Robert/0000-0002-0756-3629; Harden, Kathryn/0000-0002-1557-6737; Hotopf, Matthew/0000-0002-3980-4466; McAdams, Tom/0000-0002-6825-3499; Aaltonen, Sari/0000-0002-2873-4263; Kremen, William/0000-0002-8629-5609; Pahlen, Shandell/0000-0003-0753-4155; Llewellyn, Clare/0000-0002-0066-2827; Franz, Carol/0000-0002-8987-1755; Derom, Catherine/0000-0001-5574-796X; Willemsen, Gonneke/0000-0003-3755-0236; Rasmussen, Finn/0000-0001-7915-7809; Rebato, Esther/0000-0003-1221-8501; lee, kayoung/0000-0002-2816-554X; Sodemann, Morten/0000-0001-8992-2500; Gatz, Margaret/0000-0002-1071-9970; Boivin, Michel/0000-0001-8621-9844; Silventoinen, Karri/0000-0003-1759-3079 WOS: 000358874400002 PubMed: 26014041 For over 100 years, the genetics of human anthropometric traits has attracted scientific interest. In particular, height and body mass index (BMI, calculated as kg/m(2)) have been under intensive genetic research. However, it is still largely unknown whether and how heritability estimates vary between human populations. Opportunities to address this question have increased recently because of the establishment of many new twin cohorts and the increasing accumulation of data in established twin cohorts. We started a new research project to analyze systematically (1) the variation of heritability estimates of height, BMI and their trajectories over the life course between birth cohorts, ethnicities and countries, and (2) to study the effects of birth-related factors, education and smoking on these anthropometric traits and whether these effects vary between twin cohorts. We identified 67 twin projects, including both monozygotic (MZ) and dizygotic (DZ) twins, using various sources. We asked for individual level data on height and weight including repeated measurements, birth related traits, background variables, education and smoking. By the end of 2014, 48 projects participated. Together, we have 893,458 height and weight measures (52% females) from 434,723 twin individuals, including 201,192 complete twin pairs (40% monozygotic, 40% same-sex dizygotic and 20% opposite-sex dizygotic) representing 22 countries. This project demonstrates that large-scale international twin studies are feasible and can promote the use of existing data for novel research purposes. National Institute of Mental HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01 MH58354]; National Institute on AgingUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Aging (NIA) [1RO1-AG13662-01A2]; National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R21 AG039572]; WT Grant Foundation; University of London Central Research fund; Medical Research CouncilMedical Research Council UK (MRC) [G81/343, G120/635]; Economic and Social Research CouncilEconomic & Social Research Council (ESRC) [RES-000-22-2206]; Institute of Social Psychiatry [06/07-11]; Leverhulme Research FellowshipLeverhulme Trust [RF/2/RFG/2008/0145]; Goldsmiths; University of London; National Research Foundation of KoreaNational Research Foundation of Korea [NRF-371-2011-1B00047]; Danish Agency for Science, Technology and Innovation; Research Council for Health and Disease; Velux Foundation; US National Institute of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [P01 AG08761]; Fund of Scientific Research, FlandersFWO; Twins, a non-profit Association for Scientific Research in Multiple Births (Belgium); Global Research Network Program of the National Research Foundation [NRF 2011-220-E00006]; NIDAUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Drug Abuse (NIDA) [DA011015]; Longitudinal Twin Study [HD10333]; National Institute of Health grantsUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [NIA R01 AG018384, R01 AG018386, R01 AG022381, R01 AG022982]; Cooperative Studies Program of the Office of Research AMP; Development of the United States Department of Veterans Affairs; Centre of Research Excellence from the National Health and Medical Research CouncilNational Health and Medical Research Council of Australia [1079102]; Michigan State University from the National Institute of Mental Health (NIMH) [R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01]; Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD) [R01-HD066040]; MSU Foundation [11-SPG-2518]; California Tobacco-Related Disease Research ProgramUniversity of California System [7RT-0134H, 8RT-0107H, 6RT-0354H]; The National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [1R01ESO15150-01]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [81125007]; Australian National Health and Medical Research CouncilNational Health and Medical Research Council of Australia [437015, 607358]; Bonnie Babes Foundation [BBF20704]; Financial Markets Foundation for Children [032-2007]; Victorian Government's Operational Infrastructure Support Program; ENGAGE-European Network for Genetic and Genomic Epidemiology [201413]; National Institute of Alcohol Abuse and AlcoholismUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Alcohol Abuse & Alcoholism (NIAAA) [AA-12502, AA-00145, AA-09203]; Academy of Finland Center of Excellence in Complex Disease GeneticsAcademy of Finland [213506, 129680]; Academy of FinlandAcademy of Finland [100499, 205585, 118555, 141054, 265240, 263278, 264146]; Osaka University's International Joint Research Promotion Program; Kirikkale University Research Grant: KKUKirikkale University; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114C117]; European Research Council (ERC)European Research Council (ERC) [240994]; European Union's Seventh Framework Programmes ENGAGE ConsortiumEuropean Union (EU) [HEALTH-F4-2007-201413]; BioSHaRE EU [HEALTH-F4-2010-261433]; Seneca FoundationFundacion Seneca; Regional Agency for Science and Technology, Murcia, Spain [08633/PHCS/08, 15302/PHCS/10]; Ministry of Science and Innovation, SpainSpanish Government [PSI11560-2009]; UK Medical Research CouncilMedical Research Council UK (MRC) [G0901245]; UK Biotechnology and Biological Sciences Research CouncilBiotechnology and Biological Sciences Research Council (BBSRC) [31/D19086]; Portuguese agency for research (The Foundation for Science and Technology) [POCI/DES/56834/2004]; National Institutes of Health.United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R01 HD068435, R01 MH062375]; Wellcome TrustWellcome Trust; European Community's Seventh Framework ProgrammeEuropean Union (EU); National Institute for Health Research (NIHR) BioResource Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London; Netherlands Organization for Scientific Research (NWO)Netherlands Organization for Scientific Research (NWO); MagW/ZonMW [904-61-090, 985-10-002, 912-10-020, 904-61-193, 480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192]; VU University's Institute for Health and Care Research (EMGO+); European Research CouncilEuropean Research Council (ERC) [ERC-230374]; Avera Institute, Sioux Falls, South Dakota (USA); Cancer Research UKCancer Research UK [C1418/A7974]; [5T32DA017637-10]; [NIH RC2 HL103416]; Cancer Research UKCancer Research UK [14133]; Medical Research CouncilMedical Research Council UK (MRC) [G0901245, MC_UU_12013/1]; NNF Center for Basic Metabolic ResearchNovo Nordisk Foundation [Metabolic Genetics]; Novo Nordisk FondenNovo NordiskNovo Nordisk Foundation [NNF10CC1016515] This study was conducted within the CODATwins project (Academy of Finland #266592). Support for participating twin projects: the University of Southern California Twin Study is funded by a grant from the National Institute of Mental Health (R01 MH58354). The Carolina African American Twin Study of Aging (CAATSA) was funded by a grant from the National Institute on Aging (grant 1RO1-AG13662-01A2) to K. E. Whitfield. The NAS-NRC Twin Registry acknowledges financial support from the National Institutes of Health grant number R21 AG039572. Waves 1-3 of Genesis 12-19 were funded by the WT Grant Foundation, the University of London Central Research fund and a Medical Research Council Training Fellowship (G81/343) and Career Development Award (G120/635) to Thalia C. Eley. Wave 4 was supported by grants from the Economic and Social Research Council (RES-000-22-2206) and the Institute of Social Psychiatry (06/07-11) to Alice M. Gregory who was also supported at that time by a Leverhulme Research Fellowship (RF/2/RFG/2008/0145). Wave 5 was supported by funding to Alice M. Gregory from Goldsmiths, University of London. Anthropometric measurements of the Hungarian twins were supported by Medexpert Ltd., Budapest, Hungary. South Korea Twin Registry is supported by National Research Foundation of Korea (NRF-371-2011-1B00047). The Danish Twin Registry is supported by the National Program for Research Infrastructure 2007 from the Danish Agency for Science, Technology and Innovation, The Research Council for Health and Disease, the Velux Foundation and the US National Institute of Health (P01 AG08761). Since its origin, the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a non-profit Association for Scientific Research in Multiple Births (Belgium). Korean Twin-Family Register was supported by the Global Research Network Program of the National Research Foundation (NRF 2011-220-E00006). The Colorado Twin Registry is funded by NIDA funded center grant DA011015 and Longitudinal Twin Study HD10333; Author Huibregtse is supported by 5T32DA017637-10. The Vietnam Era Twin Study of Aging was supported by National Institute of Health grants NIA R01 AG018384, R01 AG018386, R01 AG022381, and R01 AG022982, and, in part, with resources of the VA San Diego Center of Excellence for Stress and Mental Health. The Cooperative Studies Program of the Office of Research & Development of the United States Department of Veterans Affairs has provided financial support for the development and maintenance of the Vietnam Era Twin (VET) Registry. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the NIA/NIH, or the VA. The Australian Twin Registry is supported by a Centre of Research Excellence (grant ID 1079102) from the National Health and Medical Research Council administered by the University of Melbourne. The Michigan State University Twin Registry has been supported by Michigan State University, as well as grants R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01 from the National Institute of Mental Health (NIMH), R01-HD066040 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD), and 11-SPG-2518 from the MSU Foundation. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the NIMH, the NICHD, or the National Institutes of Health.; r The California Twin Program was supported by The California Tobacco-Related Disease Research Program (7RT-0134H, 8RT-0107H, 6RT-0354H) and the National Institutes of Health (1R01ESO15150-01). The Guangzhou Twin Eye Study is supported by National Natural Science Foundation of China (grant #81125007). PETS was supported by grants from the Australian National Health and Medical Research Council (grant numbers 437015 and 607358 to JC, and RS), the Bonnie Babes Foundation (grant number BBF20704 to JMC), the Financial Markets Foundation for Children (grant no. 032-2007 to JMC), and by the Victorian Government's Operational Infrastructure Support Program. Data collection and analyses in Finnish twin cohorts have been supported by ENGAGE-European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement number 201413, National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145, and AA-09203 to R. J. Rose, the Academy of Finland Center of Excellence in Complex Disease Genetics (grant numbers: 213506, 129680), and the Academy of Finland (grants 100499, 205585, 118555, 141054, 265240, 263278 and 264146 to J. Kaprio). K. Silventoinen is supported by Osaka University's International Joint Research Promotion Program. S. Y. Oncel and F. Aliev are supported by Kirikkale University Research Grant: KKU, 2009/43 and TUBITAK grant 114C117. The Longitudinal Israeli Study of Twins was funded by the Starting Grant no. 240994 from the European Research Council (ERC) to Ariel Knafo. Data collection and research stemming from the Norwegian Twin Registry is supported, in part, from the European Union's Seventh Framework Programmes ENGAGE Consortium (grant agreement HEALTH-F4-2007-201413, and BioSHaRE EU (grant agreement HEALTH-F4-2010-261433). The Murcia Twin Registry is supported by the Seneca Foundation, Regional Agency for Science and Technology, Murcia, Spain (08633/PHCS/08 & 15302/PHCS/10) and Ministry of Science and Innovation, Spain (PSI11560-2009). The Twins Early Development Study (TEDS) is supported by a program grant (G0901245) from the UK Medical Research Council and the work on obesity in TEDS is supported in part by a grant from the UK Biotechnology and Biological Sciences Research Council (31/D19086). The Madeira data comes from the following project: genetic and environmental influences on physical activity, fitness, and health: the Madeira family study Project reference: POCI/DES/56834/2004 founded by the Portuguese agency for research (The Foundation for Science and Technology). The Boston University Twin Project is funded by grants (#R01 HD068435 #R01 MH062375) from the National Institutes of Health to K. Saudino. TwinsUK was funded by the Wellcome Trust; European Community's Seventh Framework Programme (FP7/2007-2013). The study also receives support from the National Institute for Health Research (NIHR) BioResource Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London. The University of Washington Twin Registry is supported by the grant NIH RC2 HL103416 (D. Buchwald, PI). The Netherlands Twin Register acknowledges the Netherlands Organization for Scientific Research (NWO) and MagW/ZonMW grants 904-61-090, 985-10-002, 912-10-020, 904-61-193,480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192; VU University's Institute for Health and Care Research (EMGO+); the European Research Council (ERC-230374), the Avera Institute, Sioux Falls, South Dakota (USA).; r Gemini was supported by a grant from Cancer Research UK (C1418/A7974).

Viewed from any angle—the magnitude of the quake, the number of casualties, or the scale of its destruction—the Great East Japan Earthquake of 11 March 2011, was a disaster of extreme severity unprecedented in modern Japanese history (Kazama & Narita, 2011; Meguro, 2011; Nakano et al., 2012; Ochi, Murray, & Hodgson, 2013). Many survivors had to confront painful situation such as life stress after the earthquake, tsunami, and nuclear disaster. In the event of such a disaster, saving and protecting human lives takes all precedence; therefore, acquiring support from disaster relief personnel such as health care professionals and firefighters is essential. According to the Ministry of Health, Labor and Welfare, approximately 11,266 certified health care professionals and other disaster response personnel were dispatched to the disaster-stricken region after the Great East Japan Earthquake (Ministry of Health, Labor & Welfare, 2012). Disaster response personnel supported the residents of the affected areas through a wide range of care and support, including rescue and urgent care activities immediately after the disaster and the operation of evacuation centers, recovery efforts (e.g., health survey, health checking, and so on), and provision of mental health care over the following months (Igusa et al., 2012; Kanamori, Kunishima, Tokuda, & Kaku, 2011; Nishi et al., 2012). Individuals who provide such support while living in a disaster area are likely to themselves be physically and mentally affected by the disaster, similarly to the residents in the area (Kyutoku et al., 2012; Nishizawa, Hoshide, Shinpo, & Kario, 2012; Ogawa et al., 2012). A survey of members of the Disaster Medical Assistance (DMAT) team who were dispatched after the Great East Japan Earthquake reported psychological stress over concerns about potential radiation exposure (Matsuda et al., 2012). In a survey of firefighters involved in rescue activities after the disaster, on the other hand, almost none were reported to develop posttraumatic stress disorder (PTSD; Fushimi, 2012). However, few studies have investigated the activities and health status of public health nurses who were dispatched after the disaster. This study therefore aimed to document the actual activities conducted by public health nurses during their dispatch and their health status during and after dispatch to the three prefectures most severely affected by the Earthquake.

Background: Twins and triplets fall behind singletons in cognitive and physical development. We analysed whether these differences are modified by family social position. Methods: IQ, height, body mass index (BMI) and elbow flexion, handgrip and knee extension strength were measured in Swedish men born between 1951 and 1976 during the conscription examination at 17 to 20 years of age. Information from Swedish registers on all siblings and parental socio-economic position were linked to these measures. Together, the measures were available for 1 140 329 singletons, 19 755 twins and 207 triplets. The data were analysed using regression analyses and fixed-effect models which compare twins and triplets with their singleton brothers. Results: Twins and triplets had slightly lower IQ, height, BMI and muscle strength than did singletons both at the population level as well as when compared with their singleton brothers. Although the differences between twins and triplets were small, they were largest in families with lower socio-economic position. We also found larger differences in IQ among the sons of mothers born before 1940. Conclusions: Twins and triplets fall slightly behind singletons in cognitive and physical development, even in early adulthood, but twins and triplets show no major differences. These differences are largest in families in a low socio-economic position. Our results underscore the importance of the postnatal environment in the development of twins and triplets and suggest that their parents, especially those in a low socio-economic position, need special support.

Sund, Reijo/0000-0002-6268-8117; Heikkila, Kauko/0000-0002-9256-8028; Knafo-Noam, Ariel/0000-0003-0613-1960; Montgomery, Grant W/0000-0002-4140-8139; de Freitas, Duarte Luis/0000-0001-6642-3370; ONCEL, Sevgi YURT/0000-0002-0990-292X; Fagnani, Corrado/0000-0001-5771-7772; Loos, Ruth J F/0000-0002-8532-5087; Kaprio, Jaakko/0000-0002-3716-2455; Huibregtse, Brooke M./0000-0003-0977-7249; ROMERA, JUAN FRANCISCO SANCHEZ/0000-0002-5405-6216; Colodro-Conde, Lucia/0000-0002-9004-364X; Tan, Qihua/0000-0003-3194-0030; Ordonana, Juan R./0000-0001-7779-6017; Kandler, Christian/0000-0002-9175-235X; Aliev, Fazil/0000-0001-8357-4699; Siribaddana, Sisira/0000-0001-5821-2557; Busjahn, Andreas/0000-0001-9650-6919; Tan, Qihua/0000-0003-3194-0030; Rasmussen, Finn/0000-0001-7915-7809; Silventoinen, Karri/0000-0003-1759-3079; Pedersen, Nancy/0000-0001-8057-3543; van Beijsterveldt, Toos/0000-0002-6617-4201; Franz, Carol/0000-0002-8987-1755; Rebato, Esther/0000-0003-1221-8501; Pahlen, Shandell/0000-0003-0753-4155; Harden, Kathryn/0000-0002-1557-6737; Bartels, Meike/0000-0002-9667-7555; Willemsen, Gonneke/0000-0003-3755-0236; Latvala, Antti/0000-0001-5695-117X WOS: 000412597600005 PubMed: 28975875 Whether monozygotic (MZ) and dizygotic (DZ) twins differ from each other in a variety of phenotypes is important for genetic twin modeling and for inferences made from twin studies in general. We analyzed whether there were differences in individual, maternal and paternal education between MZ and DZ twins in a large pooled dataset. Information was gathered on individual education for 218,362 adult twins from 27 twin cohorts (53% females; 39% MZ twins), and on maternal and paternal education for 147,315 and 143,056 twins respectively, from 28 twin cohorts (52% females; 38% MZ twins). Together, we had information on individual or parental education from 42 twin cohorts representing 19 countries. The original education classifications were transformed to education years and analyzed using linear regression models. Overall, MZ males had 0.26 (95% CI [0.21, 0.31]) years and MZ females 0.17 (95% CI [0.12, 0.21]) years longer education than DZ twins. The zygosity difference became smaller in more recent birth cohorts for both males and females. Parental education was somewhat longer for fathers of DZ twins in cohorts born in 1990-1999 (0.16 years, 95% CI [0.08, 0.25]) and 2000 or later (0.11 years, 95% CI [0.00, 0.22]), compared with fathers of MZ twins. The results show that the years of both individual and parental education are largely similar in MZ and DZ twins. We suggest that the socio-economic differences between MZ and DZ twins are so small that inferences based upon genetic modeling of twin data are not affected. CODATwins project (Academy of Finland) [266592]; National Health and Medical Research CouncilNational Health and Medical Research Council of Australia [1079102]; National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R01 HD068435, R01 MH062375, 1R01ESO15150-01, R21 AG039572, AA023322, HD081437, NIA R01 AG018384, R01 AG018386, R01 AG022381, R01 AG022982]; California Tobacco-Related Disease Research ProgramUniversity of California System [7RT-0134H, 8RT-0107H, 6RT-0354H]; National Institute on AgingUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Aging (NIA) [1RO1-AG13662-01A2]; Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) [340-2013-5867]; Stockholm County Council (ALF)Stockholm County Council; Swedish Heart-Lung FoundationSwedish Heart-Lung Foundation; Swedish Asthma and Allergy Association's Research Foundation; NIDAUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Drug Abuse (NIDA) [DA011015]; Longitudinal Twin Study [HD10333]; Fund of Scientific Research, Flanders and Twins; ENGAGE European Network for Genetic and Genomic Epidemiology [201413]; National Institute of Alcohol Abuse and AlcoholismUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Alcohol Abuse & Alcoholism (NIAAA) [AA-12502, AA-00145, AA-09203]; Academy of Finland Center of Excellence in Complex Disease GeneticsAcademy of Finland [213506, 129680]; Academy of FinlandAcademy of Finland [100499, 205585, 118555, 141054, 265240, 263278, 264146]; Cancer Research UKCancer Research UK [C1418/A7974]; Medexpert Ltd., Budapest, Hungary; Global Research Network Program of the National Research Foundation [NRF 2011-220-E00006]; European Research Council (ERC)European Research Council (ERC) [240994]; Michigan State University; National Institute of Mental Health (NIMH)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01]; Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD) [R01-HD066040]; MSU Foundation [11-SPG-2518]; Fundacion SenecaFundacion Seneca; Regional Agency for Science and Technology, Murcia, Spain [08633/PHCS/08, 15302/PHCS/10, 19479/PI/14]; Ministry of Science and Innovation, SpainSpanish Government [PSI2009-11560, PSI2014-56680-R]; MagW/ZonMW [904-61-090, 985-10-002, 912-10-020, 904-61-193, 480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192]; VU University's Institute for Health and Care Research (EMGO+); European Research CouncilEuropean Research Council (ERC) [ERC - 230374]; Avera Institute, Sioux Falls, South Dakota (USA); National Research Foundation of KoreaNational Research Foundation of Korea [NRF-371-2011-1 B00047]; Krkkale University Research Grant [2009/43]; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114C117]; Cooperative Studies Program of the Office of Research AMP; Development of the United States Department of Veterans Affairs; Japan Society for the Promotion of ScienceMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science [15H05105]; National Institute of Mental HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01 MH58354]; JSPS KAKENHI JP [23593419, 24792601, 26671010, 24590695, 26293128, 16K15385, 16K15978, 16K15989, 16H03261]; [5T32DA017637-11]; [POCI/DES/56834/2004]; [NIH RC2 HL103416] This study was conducted within the CODATwins project (Academy of Finland #266592). The Australian Twin Registry is supported by a Centre of Research Excellence (grant ID 1079102) from the National Health and Medical Research Council administered by the University of Melbourne. The Boston University Twin Project is funded by grants (#R01 HD068435 #R01 MH062375) from the National Institutes of Health to K. Saudino. California Twin Program was supported by The California Tobacco-Related Disease Research Program (7RT-0134H, 8RT-0107H, 6RT-0354H) and the National Institutes of Health (1R01ESO15150-01). The Carolina African American Twin Study of Aging (CAATSA) was funded by a grant from the National Institute on Aging (grant 1RO1-AG13662-01A2) to K. E. Whitfield. The CATSS-Study is supported by the Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) framework grant no 340-2013-5867, grants provided by the Stockholm County Council (ALF-projects), the Swedish Heart-Lung Foundation and the Swedish Asthma and Allergy Association's Research Foundation. Colorado Twin Registry is funded by NIDA funded center grant DA011015 and Longitudinal Twin Study HD10333; Author Huibregtse is supported by 5T32DA017637-11. Since its origin, the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a non-profit Association for Scientific Research in Multiple Births (Belgium). Data collection and analyses in Finnish twin cohorts have been supported by ENGAGE European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement number 201413, National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145, and AA-09203 to R J Rose, the Academy of Finland Center of Excellence in Complex Disease Genetics (grant numbers: 213506, 129680), and the Academy of Finland (grants 100499, 205585, 118555, 141054, 265240, 263278, and 264146 to J Kaprio). Gemini was supported by a grant from Cancer Research UK (C1418/A7974). Anthropometric measurements of the Hungarian twins were supported by Medexpert Ltd., Budapest, Hungary. Korean Twin-Family Register was supported by the Global Research Network Program of the National Research Foundation (NRF 2011-220-E00006). Longitudinal Israeli Study of Twins was funded by the Starting Grant no. 240994 from the European Research Council (ERC) to Ariel Knafo. The Michigan State University Twin Registry has been supported by Michigan State University, as well as grants R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01 from the National Institute of Mental Health (NIMH), R01-HD066040 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD), and 11-SPG-2518 from the MSU Foundation. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the NIMH, the NICHD, or the National Institutes of Health. The Murcia Twin Registry is supported by Fundacion Seneca, Regional Agency for Science and Technology, Murcia, Spain (08633/PHCS/08, 15302/PHCS/10 & 19479/PI/14) and Ministry of Science and Innovation, Spain (PSI2009-11560 & PSI2014-56680-R). The NAS-NRC Twin Registry acknowledges financial support from the National Institutes of Health grant number R21 AG039572.; r Netherlands Twin Register acknowledges the Netherlands Organization for Scientific Research (NWO) and MagW/ZonMW grants 904-61-090, 985-10-002, 912-10-020, 904-61-193,480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192; VU University's Institute for Health and Care Research (EMGO+); the European Research Council (ERC - 230374), the Avera Institute, Sioux Falls, South Dakota (USA). Madeira data comes from the following project: Genetic and environmental influences on physical activity, fitness, and health: the Madeira family study. Project reference: POCI/DES/56834/2004. Founded by the Portuguese agency for research (The Foundation for Science and Technology [FCT]). South Korea Twin Registry is supported by National Research Foundation of Korea (NRF-371-2011-1 B00047). The Texas Twin Project is currently funded by grants AA023322 and HD081437 from the National Institutes of Health. S. Y. oncel and F. Aliev are supported by Krkkale University Research Grant: KKU, 2009/43 and TUBITAK grant 114C117. Washington State Twin Registry (formerly the University of Washington Twin Registry) was supported in part by grant NIH RC2 HL103416 (D. Buchwald, PI). Vietnam Era Twin Study of Aging was supported by National Institute of Health grants NIA R01 AG018384, R01 AG018386, R01 AG022381, and R01 AG022982, and, in part, with resources of the VA San Diego Center of Excellence for Stress and Mental Health. The Cooperative Studies Program of the Office of Research & Development of the United States Department of Veterans Affairs has provided financial support for the development and maintenance of the Vietnam Era Twin (VET) Registry. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the NIA/NIH, or the VA. The West Japan Twins and Higher Order Multiple Births Registry was supported by Grant-in-Aid for Scientific Research (B) (grant number 15H05105) from the Japan Society for the Promotion of Science. The University of Southern California Twin Study is funded by a grant from the National Institute of Mental Health (R01 MH58354). Osaka University Aged Twin Registry is supported by grants from JSPS KAKENHI JP (23593419, 24792601, 26671010, 24590695, 26293128, 16K15385, 16K15978, 16K15989, 16H03261).

Loos, Ruth J F/0000-0002-8532-5087; Huibregtse, Brooke M./0000-0003-0977-7249; Busjahn, Andreas/0000-0001-9650-6919; Skytthe, Axel E/0000-0002-8629-4913; Heikkila, Kauko/0000-0002-9256-8028; Haworth, Claire/0000-0002-8608-289X; Hjelmborg, Jacob/0000-0001-9630-9149; Sund, Reijo/0000-0002-6268-8117; Aliev, Fazil/0000-0001-8357-4699; Fagnani, Corrado/0000-0001-5771-7772; Kaprio, Jaakko/0000-0002-3716-2455; Knafo-Noam, Ariel/0000-0003-0613-1960; Montgomery, Grant W/0000-0002-4140-8139; Moller, Soren/0000-0003-0858-4269; ONCEL, Sevgi YURT/0000-0002-0990-292X; Duncan, Glen/0000-0001-6909-1869; Medland, Sarah E/0000-0003-1382-380X; Kandler, Christian/0000-0002-9175-235X; Christensen, Kaare/0000-0002-5429-5292; Magnusson, Patrik/0000-0002-7315-7899; mangino, massimo/0000-0002-2167-7470; Bartels, Meike/0000-0002-9667-7555; de Freitas, Duarte Luis/0000-0001-6642-3370; Harden, Kathryn/0000-0002-1557-6737; Derom, Catherine/0000-0001-5574-796X; Plomin, Robert/0000-0002-0756-3629; Silventoinen, Karri/0000-0003-1759-3079; Rasmussen, Finn/0000-0001-7915-7809; Boivin, Michel/0000-0001-8621-9844; Saffery, Richard/0000-0002-9510-4181; Pahlen, Shandell/0000-0003-0753-4155; van Beijsterveldt, Toos/0000-0002-6617-4201; Rebato, Esther/0000-0003-1221-8501; Pedersen, Nancy/0000-0001-8057-3543; Aaltonen, Sari/0000-0002-2873-4263; Llewellyn, Clare/0000-0002-0066-2827; Kyvik, Kirsten Ohm/0000-0003-2981-0245; Sodemann, Morten/0000-0001-8992-2500; Willemsen, Gonneke/0000-0003-3755-0236; D'Ippolito, Cristina/0000-0001-7902-9380; McAdams, Tom/0000-0002-6825-3499 WOS: 000378317900001 PubMed: 27333805 Height variation is known to be determined by both genetic and environmental factors, but a systematic description of how their influences differ by sex, age and global regions is lacking. We conducted an individual-based pooled analysis of 45 twin cohorts from 20 countries, including 180,520 paired measurements at ages 1-19 years. The proportion of height variation explained by shared environmental factors was greatest in early childhood, but these effects remained present until early adulthood. Accordingly, the relative genetic contribution increased with age and was greatest in adolescence (up to 0.83 in boys and 0.76 in girls). Comparing geographic-cultural regions (Europe, North-America and Australia, and East-Asia), genetic variance was greatest in North-America and Australia and lowest in East-Asia, but the relative proportion of genetic variation was roughly similar across these regions. Our findings provide further insights into height variation during childhood and adolescence in populations representing different ethnicities and exposed to different environments. Academy of FinlandAcademy of Finland [266592, 100499, 205585, 118555, 141054, 265240, 263278, 264146]; National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R01 HD068435, R01 MH062375, 1R01ESO15150-01, AA023322, HD081437, R21 AG039572]; California Tobacco-Related Disease Research ProgramUniversity of California System [7RT-0134H, 8RT-0107H, 6RT-0354H]; Special Fund for Health Scientific Research in the Public Welfare, China [201502006]; NIDAUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Drug Abuse (NIDA) [DA011015, HD10333]; National Program for Research Infrastructure from the Danish Agency for Science, Technology and Innovation; Research Council for Health and Disease; Velux Foundation; US National Institute of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [P01 AG08761]; Fund of Scientific Research, Flanders and Twins; NGAGE-European Network for Genetic and Genomic Epidemiology [FP7-HEALTH-F4-2007, 201413]; National Institute of Alcohol Abuse and AlcoholismUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Alcohol Abuse & Alcoholism (NIAAA) [AA-12502, AA-00145, AA-09203]; Academy of Finland Center of Excellence in Complex Disease GeneticsAcademy of Finland [213506, 129680]; Osaka University's International Joint Research Promotion Program; Cancer Research UKCancer Research UK [C1418/A7974]; WT Grant Foundation; University of London Central Research fund; Medical Research Council Training FellowshipMedical Research Council UK (MRC) [G81/343, G120/635]; Economic and Social Research CouncilEconomic & Social Research Council (ESRC) [RES-000-22-2206]; Institute of Social Psychiatry [06/07-11]; Leverhulme Research FellowshipLeverhulme Trust [RF/2/RFG/2008/0145]; Goldsmiths, University of London; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [81125007]; Medexpert Ltd., Budapest, Hungary; European Research Council (ERC)European Research Council (ERC) [240994]; Michigan State University; National Institute of Mental Health (NIMH)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01]; Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD) [R01-HD066040]; MSU Foundation [11-SPG-2518]; Netherlands Organization for Scientific Research (NWO)Netherlands Organization for Scientific Research (NWO); MagW/ZonMW [904-61-090, 985-10-002, 912-10-020, 904-61-193, 480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192]; VU University's Institute for Health and Care Research (EMGO+); European Research CouncilEuropean Research Council (ERC) [ERC-230374]; Avera Institute, Sioux Falls, South Dakota (USA); Australian National Health and Medical Research CouncilNational Health and Medical Research Council of Australia [437015, 607358]; Bonnie Babes Foundation [BBF20704]; Financial Markets Foundation for Children [032-2007]; Victorian Government's Operational Infrastructure Support Program; Portuguese agency for research (The Foundation for Science and Technology [FCT]) [POCI/DES/56834/2004]; Fonds Quebecois de la Recherche sur la Societe et la CultureFQRNT; Fonds de la Recherche en Sante du QuebecFonds de la Recherche en Sante du Quebec; Social Science and Humanities Research Council of Canada; National Health Research Development Program; Canadian Institutes for Health ResearchCanadian Institutes of Health Research (CIHR); Sainte-Justine Hospital's Research Center; Canada Research Chair ProgramCanada Research Chairs; National Research Foundation of KoreaNational Research Foundation of Korea [NRF-371-2011-1 B00047]; UK Medical Research CouncilMedical Research Council UK (MRC) [G0901245]; UK Biotechnology and Biological Sciences Research CouncilBiotechnology and Biological Sciences Research Council (BBSRC) [31/D19086]; Kirikkale University Research Grant: KKUKirikkale University [2009/43]; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114C117]; Wellcome TrustWellcome Trust; European Community's Seventh Framework Programme (FP7)European Union (EU); National Institute for Health Research (NIHR) BioResource Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London; National Institute of Mental HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Mental Health (NIMH) [R01 MH58354]; NIHUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [RC2 HL103416]; Japan Society for the Promotion of ScienceMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science [15H05105]; [5T32DA017637-11]; Medical Research CouncilMedical Research Council UK (MRC) [G19/2, MR/M021475/1, G120/635, G0500079, G0901245]; NNF Center for Basic Metabolic ResearchNovo Nordisk Foundation [Metabolic Genetics]; Novo Nordisk FondenNovo NordiskNovo Nordisk Foundation [NNF10CC1016515] This study was conducted within the CODATwins project (Academy of Finland #266592). Support for participating twin projects: The Boston University Twin Project is funded by grants (#R01 HD068435 #R01 MH062375) from the National Institutes of Health to K. Saudino. California Twin Program was supported by The California Tobacco-Related Disease Research Program (7RT-0134H, 8RT-0107H, 6RT-0354H) and the National Institutes of Health (1R01ESO15150-01). Chinese National Twin Registry is funded by Special Fund for Health Scientific Research in the Public Welfare (Project No: 201502006), China. Colorado Twin Registry is funded by NIDA funded center grant DA011015, & Longitudinal Twin Study HD10333; Author Huibregtse is supported by to 5T32DA017637-11. Danish Twin Registry is supported by the National Program for Research Infrastructure 2007 from the Danish Agency for Science, Technology and Innovation, The Research Council for Health and Disease, the Velux Foundation and the US National Institute of Health (P01 AG08761). Since its origin the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a non-profit Association for Scientific Research in Multiple Births (Belgium). Data collection and analyses in Finnish twin cohorts have been supported by ENGAGE-European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement number 201413, National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145, and AA-09203 to RJ Rose, the Academy of Finland Center of Excellence in Complex Disease Genetics (grant numbers: 213506, 129680), and the Academy of Finland (grants 100499, 205585, 118555, 141054, 265240, 263278 and 264146 to J. Kaprio). K. Silventoinen is supported by Osaka University's International Joint Research Promotion Program. Gemini was supported by a grant from Cancer Research UK (C1418/A7974). Waves 1-3 of Genesis 12-19 were funded by the WT Grant Foundation, the University of London Central Research fund and a Medical Research Council Training Fellowship (G81/343) and Career Development Award (G120/635) to Thalia C. Eley. Wave 4 was supported by grants from the Economic and Social Research Council (RES-000-22-2206) and the Institute of Social Psychiatry (06/07-11) to Alice M. Gregory who was also supported at that time by a Leverhulme Research Fellowship (RF/2/RFG/2008/0145). Wave 5 was supported by funding to Alice M. Gregory from Goldsmiths, University of London. Guangzhou Twin Eye Study is supported by National Natural Science Foundation of China (grant #81125007). Anthropometric measurements of the Hungarian twins were supported by Medexpert Ltd., Budapest, Hungary. Longitudinal Israeli Study of Twins was funded by the Starting Grant no. 240994 from the European Research Council (ERC) to Ariel Knafo. The Michigan State University Twin Registry has been supported by Michigan State University, as well as grants R01-MH081813, R01-MH0820-54, R01-MH092377-02, R21-MH070542-01, R03-MH63851-01 from the National Institute of Mental Health (NIMH), R01-HD066040 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD), and 11-SPG-2518 from the MSU Foundation. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the NIMH, the NICHD, or the National Institutes of Health. The NAS-NRC Twin Registry acknowledges financial support from the National Institutes of Health grant number R21 AG039572.; Netherlands Twin Register acknowledges the Netherlands Organization for Scientific Research (NWO) and MagW/ZonMW grants 904-61-090, 985-10-002, 912-10-020, 904-61-193,480-04-004, 463-06-001, 451-04-034, 400-05-717, Addiction-31160008, Middelgroot-911-09-032, Spinozapremie 56-464-14192; VU University's Institute for Health and Care Research (EMGO+); the European Research Council (ERC-230374), the Avera Institute, Sioux Falls, South Dakota (USA). PETS was supported by grants from the Australian National Health and Medical Research Council (grant numbers 437015 and 607358 to J. C. and R.S.), the Bonnie Babes Foundation (grant number BBF20704 to J. M. C.), the Financial Markets Foundation for Children (grant no. 032-2007 to J. M. C.), and by the Victorian Government's Operational Infrastructure Support Program. Madeira data comes from the following project: Genetic and environmental influences on physical activity, fitness and health: the Madeira family study Project reference: POCI/DES/56834/2004 Founded by the Portuguese agency for research (The Foundation for Science and Technology [FCT]). The Quebec Newborn Twin Study acknowledges financial support from the Fonds Quebecois de la Recherche sur la Societe et la Culture, the Fonds de la Recherche en Sante du Quebec, the Social Science and Humanities Research Council of Canada, the National Health Research Development Program, the Canadian Institutes for Health Research, Sainte-Justine Hospital's Research Center, and the Canada Research Chair Program (Michel Boivin). South Korea Twin Registry is supported by National Research Foundation of Korea (NRF-371-2011-1 B00047). The Texas Twin Project is currently funded by grants AA023322 and HD081437 from the National Institutes of Health. The Twins Early Development Study (TEDS) is supported by a program grant (G0901245) from the UK Medical Research Council and the work on obesity in TEDS is supported in part by a grant from the UK Biotechnology and Biological Sciences Research Council (31/D19086). S.Y. Oncel and F. Aliev are supported by Kirikkale University Research Grant: KKU, 2009/43 and TUBITAK grant 114C117. TwinsUK was funded by the Wellcome Trust; European Community's Seventh Framework Programme (FP7/2007-2013). The study also receives support from the National Institute for Health Research (NIHR) BioResource Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London. The University of Southern California Twin Study is funded by a grant from the National Institute of Mental Health (R01 MH58354). Washington State Twin Registry (formerly the University of Washington Twin Registry) was supported in part by grant NIH RC2 HL103416 (D. Buchwald, PI). The West Japan Twins and Higher Order Multiple Births Registry was supported by Grant-in-Aid for Scientific Research (B) (grant number 15H05105) from the Japan Society for the Promotion of Science.

Background: Chest circumference (CC) is suggested to be a good indicator of early life nutrition, but little is known on the heritability of CC. Thus we analysed the effects of genetic and environmental factors on the development of CC in Japanese infants. Methods: CC was measured longitudinally from birth until 1 year of age in a cohort of 211 monozygotic and 160 dizygotic complete Japanese twin pairs born in 1989–2002. The data were analysed using applications of structural linear equation modelling for twin data. Results: No sex-specific differences in the variance components were found. Environmental factors unique to each twin explained the major part of the variation of CC at birth whereas environmental factors shared by co-twins were more important at 1–3 months of age. From 3 months of age, the effect of genetic factors become steadily stronger and they explained the majority of the variation at 1 year of age. Strong genetic continuity in the development of CC was found, but also new sets of genes were activated during the first year of life. The origin of the environmental part of the variation could be tracked before 3 months of age. A substantial part of common and specific environmental factors affecting CC affected also birthweight. Conclusions: CC is sensitive to intrauterine environmental factors, but these effects diminish during the first year of life, at least if postnatal environment is good. CC can be a useful indicator when identifying newborns who have suffered suboptimal pre-natal conditions.

We analyzed the characteristics associated with the growth in height of Japanese triplets from birth to 12 years of age. The study included 376 mothers and their 1,128 triplet children, who were born between 1978 and 2006. Data were collected through a mailed questionnaire sent to the mothers asking for information recorded in medical records. For these births, data on triplets' length and height growth, gestational age, sex, parity, maternal age at delivery, and maternal height were obtained from records in the Maternal and Child Health Handbooks and records in the school which children receive health check-ups. The height deficit of the triplets compared to the general population of Japan remained between 2% and 5% until 12 years of age. Moreover, at 12 years of age, the differences of height between the general population and triplets were approximately -3.6 cm for male and -4.4 cm for female. Maternal height showed the strongest contribution to height of triplets from 6 to 12 years of age. In conclusion, triplets remain shorter than singletons until 12 years of age.

目的：国内において報告されてきた笑いの効果を身体面，精神面の二方向から概観し，看護の場で笑いを用いる有効性を提示することを目的とした．方法：引用文献の検索には，医学中央雑誌刊行会から，“笑い”or“ユーモア”をキーワードとして1980年以降，2009年5月までで検索を行い，29件採用した．また，国際誌はPubMedを用い，2000年以降，2009年5月までの文献からキーワード“laughter”and“effect”で検索し，20件を採用した．結果：笑いの身体面の効果としては，笑い体験によるNK細胞活性ならびにアレルギー反応などの免疫系に関して効果があったという報告が最も多く，その他疼痛緩和，血糖上昇抑制作用があることが報告されていた．また笑いの精神的効果として，ストレスコーピング，不安ならびに緊張の緩和などの効果が報告されていた．結論：笑いは，身体面と精神面両方での効果が期待できる．しかし，看護ケアとして笑いの効果を検討した研究は少なく，今後，看護師による笑いに関する介入研究の成果が期待される．

We analyzed the genetic architecture of prepubertal development of relative weight to height in 216 monozygotic and 159 dizygotic complete Japanese twin pairs (52% girls). Ponderal index at birth (kg/m(3)) and body mass index (BMI, kg/m(2)) from 1 to 11 years of age were used. Additive genetic factors explained the major proportion (52-74%) of the variation of BMI from 1 to 11 years of age. Environmental factors common to both co-twins also showed some effect (7-28%), but at most ages this was not statistically significant. Strong genetic tracking was found for BMI from 1 to 11 years of age, but there was also evidence for a persistent effect of common environmental factors. Our results suggest that the genetic architecture of BMI development in the Japanese population is generally similar to that found in previous twin studies in Caucasian populations.

We analyzed the characteristics associated with the growth in length and height of Japanese triplets from birth to 6 years of age and present the growth charts for them. The study included 354 mothers and their 1,061 triplet children, who were born between 1978 and 2006. Data were collected through a mailed questionnaire sent to the mothers asking for information recorded in medical records. For these births, data on triplets' length and height growth, gestational age, sex, parity, and maternal age at delivery were obtained from records in the Maternal and Child Health Handbooks, which is provided by the authorities after a report of pregnancy. Birth length showed the strongest contribution to height of triplets from 1 to 6 years of age. In addition, birthweight was also a significant contributing factor to height from 1 to 3 years of age. Compared to the 50th percentile of the growth standard for the general population of Japan, the length and height deficit of the triplets was approximately 15% at birth (male, –7.0 cm; female, –7.0 cm), decreased within the first year of age, and fluctuated between 2 and 5% until 6 years of age (male, –3.7 cm; female, –3.3 cm). In conclusion, triplets have lower birth length and subsequent height than singletons. In spite of the catch-up growth during the first year of life, they are behind singletons even in mid-childhood. This study provides height growth curves for triplets.

We analyzed birth order differences in means and variances of height and body mass index (BMI) in monozygotic (MZ) and dizygotic (DZ) twins from infancy to old age. The data were derived from the international CODATwins database. The total number of height and BMI measures from 0.5 to 79.5 years of age was 397,466. As expected, first-born twins had greater birth weight than second-born twins. With respect to height, first-born twins were slightly taller than second-born twins in childhood. After adjusting the results for birth weight, the birth order differences decreased and were no longer statistically significant. First-born twins had greater BMI than the second-born twins over childhood and adolescence. After adjusting the results for birth weight, birth order was still associated with BMI until 12 years of age. No interaction effect between birth order and zygosity was found. Only limited evidence was found that birth order influenced variances of height or BMI. The results were similar among boys and girls and also in MZ and DZ twins. Overall, the differences in height and BMI between first- and second-born twins were modest even in early childhood, while adjustment for birth weight reduced the birth order differences but did not remove them for BMI.

This study was performed using population-based data to analyze whether motor development in early life is different between singletons and twins in Japan. For better comparison and investigation, we divided the 2 groups into a group with a birthweight of 2.5 kg or greater (subgroup A) and a group with a birthweight of less than 2.5 kg (subgroup B), respectively. We analyzed the database of medical check-ups for children aged 3 years between April 2001 and July 2004. They received medical checkups at 4 months, 1.5, and 3 years of age. Children who were suspected of having neurological abnormality or disability were referred to specialists and excluded from the database. The data of 14,132 children were analyzed. Among these, 13,040 (92.3%) children were singletons in subgroup A, 75 (0.5%) were twins in subgroup A, 866 (6.1%) were singletons in subgroup B and 151 (1.1%) were twins in subgroup B. The mean age at achieving milestones was slower in twins of subgroup A for each developmental outcome than singletons of subgroup A, and the difference between twins and singletons was significant after adjustment for rolling over. On the contrary, after adjusting for a confounding factor (gestational age), singletons of subgroup B attained motor development facilitating walking independently slower than twins of subgroup B. There were different tendencies in the results regarding the motor development of subjects of subgroup A and that of subjects of subgroup B.

Background:The occurrence of multiple births has been recognized as a risk factor for child maltreatment. However, few population-based studies have examined the relationship between multiple births and child maltreatment. This study aimed to evaluate the degree of risk of child maltreatment among singletons and multiple births in Japan and to identify factors associated with increased risk.Methods:Using population-based data, we analyzed the database of records on child maltreatment and medical checkups for infants aged 1.5 years filed at Nishinomiya City Public Health Center between April 2007 and March 2011. To protect personal information, the data were transferred to anonymized electronic files for analysis.Results:After adjusting by logistic regression for each associated factor and gestation number, multiples themselves were not associated with the risk of child maltreatment. However, compared with singletons, multiples had a significantly higher rate of risk factors for child maltreatment, including low birth weight and neural abnormality. Moreover, compared with mothers of singleton, mothers of twins had a significantly higher rate of poor health, which is a risk factor of child maltreatment.Conclusion:Multiples were not associated with the risk of child maltreatment. However, compared with singletons, multiples and their mothers had a significantly higher rate of risk factors of child maltreatment.

This study was performed to determine the rates of breastfeeding among singletons, twins and triplets in Japan, and identify factors associated with the decision to breastfeed or bottle-feed. We analyzed a database of medical check-up of infants aged 3 to 6 months between April 2001 and July 2004 in Nishinomiya City in Japan. This medical check-up is given to almost 100% of infants in Japan and the data of 15,262 infants were analyzed. Among these, 14,963 (98.0%) were singletons, 290 (1.9%) were twins and 9 (0.1%) were triplets. Exclusive breast-feeding was chosen by 6680 (43.8%) mothers, mixed-feeding by 4645 (30.4%) mothers, and bottle-feeding with formula milk only by 3900 (25.6%) mothers. The rate of exclusive breastfeeding among twins or triplets was significantly lower than among singleton babies: 4.1% among twins or triplets, and 44.7% among singletons. Moreover, twins and triplets were independently associated with a higher rate of bottle-feeding: the odds ratio indicated that mothers who had twins or triplets were 2.44 times more likely to choose bottle-feeding with formula milk only than those who had singletons. Sucking ability at birth was associated with a higher rate of bottle-feeding: the odds ratio indicated that mothers who had infants with poor sucking ability at birth were 1.56 times more likely to choose bottle-feeding as those who had infants with normal sucking ability.

The aims of this study were to identify factors associated with birthweight, birth length and head circumference for triplets, and analyze these body size parameters at birth, especially head circumference, according to gestational age. The subjects of this study were 370 mothers and their 1109 triplet children (excluding one stillborn infant) who were born between 1978 and 2002. The gestational age proved to be the strongest contributing factor to birthweight, birth length and head circumference of the triplets. Moreover, sex was a significant factor affecting birthweight, birth length and head circumference. Male neonates had a higher birthweight, longer birth length and greater head circumference than female neonates. Birth order in triplets also had a significant effect on birthweight and head circumference. Lower birth- order neonates had a higher birthweight and greater head circumference. An effect of maternal pregravid body mass index (BMI) on both birth- weight and birth length was observed. The birthweights of triplets born to women whose pregravid BMIs were more than 26.0 kg/m2 weighed an average of 150 g more than those of triplets born to women whose pregravid BMIs were less than 19.8 kg/m2, and the birth length of triplets born to women whose pregravid BMIs were more than 26.0 kg/m2 averaged 1.5 cm longer than those of triplets born to women whose pregravid BMIs were less than 19.8 kg/m2. Concerning head circumference, the median head circumference of male neonates was approximately 0.5 cm longer than female neonates. Compared to singleton neonates, the median head circumference of triplets was almost the same.

BACKGROUND: The purpose of this study was to analyze the characteristics of the physical growth of twins in childhood and to present growth charts of Japanese twins. METHODS: The subjects consisted of 2029 pairs of normally developed Japanese twins. Growth data were obtained by mailed or hand-distributed questionnaires. Factors that affect body weight and height/length at selected ages were analyzed by stepwise regression analysis. Selected percentiles o body weight, height/length, and body mass index were calculated according to sex, and growth curves were drawn using a spline function. The size deficit of the twins compared to the standards for the general population of Japan was calculated. RESULTS: Gestational age, parity, zygosity, and birth order affected physical growth in varying degrees, although the overall effects themselves were small and mostly disappeared by one year of age. Growth charts of the twins present growth at selected percentiles from birth to 6 years of age according to sex. The size deficit of the twins was largest at birth: more than 20% for weight and approximately 6% for length compared to the 50th percentile of the standard for the general population of Japan. These deficits decreased rapidly in the first 6 to 12 months, and were found to be as low as 0-2% at 4 to 6 years of age. CONCLUSION: Growth charts specifically for twins are needed, at least for the first 1 to 3 years of age but not beyond the age of 6 years.

The purpose of this study was to clarify the characteristic child-rearing problems for mothers of multiple children who conceived after infertility treatment as compared to mothers of multiple children who conceived spontaneously. The subjects were 990 mothers of multiple children: 359 who conceived after infertility treatment and 631 who conceived spontaneously. Mothers who conceived after infertility treatment were more delighted when informed of a multiple pregnancy than those who conceived spontaneously. In addition, with respect to anxiety during twin pregnancies, mothers of twins who conceived after infertility treatment showed lower rates of anxiety about nursing the infants and economic concerns than those of twins who conceived spontaneously. However, after delivery, mothers who conceived after infertility treatment showed a higher rate of depressive symptoms than those who conceived spontaneously. After adjusting for each associated factor using logistic regression, the risk of depressive symptoms in mothers who conceived after infertility treatment was significantly associated with disabled multiple children and the methods for alleviating stress. The odds ratio indicated that mothers with at least one disabled child were twice as likely to have depressive symptoms as mothers with no disabled children. Furthermore, the odds ratio indicated that mothers who used no methods for alleviating stress were twice as likely to have depressive symptoms than those who did.

Length and weight in infancy are associated with neurodevelopment, but less is known about growth in other anthropometric measures. In this study we analyzed how the development in length, weight, head circumference, and chest circumference over infancy is associated with motor development in early childhood, using a twin study design. Information on physical development over infancy and the age at achievement of eight developmental milestones over early childhood was collected for 370 Japanese twin pairs. Linear mixed models were used to analyze how physical development is associated with motor development between individual twins, as well as within twin pairs, adjusting the results for shared maternal and postnatal environmental factors. Delayed motor development was associated with smaller body size over infancy, and we also found some suggestive evidence that it was associated with catch-up growth as well. When studying the associations within twin pairs discordant for motor development, similar associations were found. However, chest circumference showed the most robust association within discordant twin pairs. Smaller body size and rapid catch-up growth are associated with delayed motor development. When studying these associations within twin pairs and thus adjusting the results for gestational age as well as many other maternal and postnatal environmental factors, chest circumference showed the most robust association. Chest circumference, rarely used in developed countries, can offer additional information on prenatal conditions relevant for further motor development not achieved by more traditional anthropometric measures.

Objectives: It is important to note that until now most of the Japanese government services for maternal welfare and child-rearing are for mothers of first children. However, as the number of children increases, the burden of care increases. Therefore, this study aimed to determine the factors that affect child-rearing uneasiness of mothers with their first child and those with two or more children, by analyzing data obtained from mothers at the 3-month health checkup after delivery in Japan. Study design: Cross-sectional design Methods: From April 2005 to December 2009, 2552 infants underwent health checkups designed for infants. The questionnaire included the following maternal factors: maternal age at delivery, birth order, fatigue, disturbed sleep, anorexia, depression, low energy, loneliness, uneasiness, irritation, large gap between reality and perception, financial anxiety, child-rearing support, individuals who can provide advice concerning child-rearing. Results: It was found that in the first child group, maternal uneasiness was affected by fatigue (OR=3.843), disturbed sleep (OR=2.155), mothers’ loneliness (OR=3.016), feeling a large gap between reality and perception (OR=2.875), feeling irritated (OR=2.093) and financial worry (OR=2.493) and experience of child’s sickness (OR=1.259). On the other hand, in the second or later child group, maternal uneasiness was affected by fatigue (OR=3.781), mothers’ loneliness (OR=3.321), feeling irritated (OR=2.397) and financial worry (OR=2.675), experience of child’s sickness (OR=1.390) and mothers’ deliveries pathologies (OR=1.396). Conclusions: It is likely that maternal uneasiness with the first child and with the second or later child was affected same factors except a few factors. In Japan, efforts to create a society where parents can give birth and raise children without worry have started. It is very important for families with children to be able to choose and utilize support and services suited to them.

This study investigated the prevalence of depression and health problems in caregivers for the disabled elderly at home, and identified factors associated with the risk of depression. Four hundred thirty-four caregivers for disabled elderly persons in a suburban city were surveyed by in-home interviews. Two hundred ten non-caregivers were also interviewed as an age and gender-matched control group. Overall, 16.8% of caregivers met the DSM-III-R criteria for major depression and 10.6% met the criteria for depressive disorders not otherwise specified, for a total of 27.4% meeting the criteria for affective disorders, while 8.6% of controls met the criteria for depressive disorders not otherwise specified. The prevalence of major depression in caregivers was associated with mental problems and ADL limitations of the elderly. Moreover, non-cooperation by other family members or relatives contributed to an increase in the prevalence of depression. Caregivers who met the criteria for major depression had a higher frequency and longer duration of upper respiratory infections than other caregivers or controls, and showed greater fatigue than the other caregivers or controls. Approximately 90% of caregivers who met the criteria for major depression had also insomnia. Overall, it was shown that caregivers who met the criteria for major depressin had not only emotional distress but also higher morbidity.

Twins and triplets fall behind singletons in cognitive and physical development. We analysed whether these differences are modified by family social position.IQ, height, body mass index (BMI) and elbow flexion, handgrip and knee extension strength were measured in Swedish men born between 1951 and 1976 during the conscription examination at 17 to 20 years of age. Information from Swedish registers on all siblings and parental socio-economic position were linked to these measures. Together, the measures were available for 1,140,329 singletons, 19,55 twins and 207 triplets. The data were analysed using regression analyses and fixed-effect models which compare twins and triplets with their singleton brothers.Twins and triplets had slightly lower IQ, height, BMI and muscle strength than did singletons both at the population level as well as when compared with their singleton brothers. Although the differences between twins and triplets were small, they were largest in families with lower socio-economic position. We also found larger differences in IQ among the sons of mothers born before 1940.Twins and triplets fall slightly behind singletons in cognitive and physical development, even in early adulthood, but twins and triplets show no major differences. These differences are largest in families in a low socio-economic position. Our results underscore the importance of the postnatal environment in the development of twins and triplets and suggest that their parents, especially those in a low socio-economic position, need special support.

We aimed to analyze the characteristics of development of relative weight in Japanese triplets from birth until 12 years of age. Data were collected through a mailed questionnaire sent to mothers of triplets asking for information recorded in medical records. Altogether we had information on 1,061 triplet children of 354 mothers born between 1978 and 2006. For these births, data on triplets’ height and weight growth, gestational age, sex, parity, and maternal age at delivery were obtained from records in the maternal and child health handbooks and records from the schools where children receive health check-ups. In addition, information on maternal height and weight was obtained. Triplets have a lower ponderal index at birth and lower body mass index (BMI) compared with the general population until 12 years of age, except for the period during 1 and 3 years of age. Moreover, birth weight had the strongest contribution to BMI of triplets until 6 years of age. After 9 years of age, maternal BMI was a significant factor affecting BMI of triplets.