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Background The 3D Cohort Study (Design, Develop, Discover) was established to help bridge knowledge gaps about the links between various adverse exposures during pregnancy with birth outcomes and later health outcomes in children. Methods Pregnant women and their partners were recruited during the first trimester from nine sites in Quebec and followed along with their children through to 2 years of age. Questionnaires were administered during pregnancy and post‐delivery to collect information on demographics, mental health and life style, medical history, psychosocial measures, diet, infant growth, and neurodevelopment. Information on the delivery and newborn outcomes were abstracted from medical charts. Biological specimens were collected from mothers during each trimester, fathers (once during the pregnancy), and infants (at delivery and 2 years of age) for storage in a biological specimen bank. Results Of the 9864 women screened, 6348 met the eligibility criteria and 2366 women participated in the study (37% of eligible women). Among women in the 3D cohort, 1721 of their partners (1704 biological fathers) agreed to participate (73%). Two thousand two hundred and nineteen participants had a live singleton birth (94%). Prenatal blood and urine samples as well as vaginal secretions were collected for ≥98% of participants, cord blood for 81% of livebirths, and placental tissue for 89% of livebirths. Conclusions The 3D Cohort Study combines a rich bank of multiple biological specimens with extensive clinical, life style, and psychosocial data. This data set is a valuable resource for studying the developmental etiology of birth and early childhood neurodevelopmental outcomes.

Evidence points to an association between a mother's place of residence and her newborn's health, independent of individual characteristics. Neighbourhood constructs such as immigrant density, deprivation and crime have all been separately associated with birth outcomes. Little research has considered the joint influence of variables representing a spectrum of neighbourhood constructs. Subjective vs. objective measures of neighbourhood constructs (e.g. reported vs. perceived crime) are often not considered. We sought to evaluate the relationship between neighbourhood measures of reported crime, neighbourhood perceived security, immigrant density, material/social deprivation, residential stability and the odds of small-for-gestational-age (SGA) birth in an urban setting in Canada. Neighbourhood was defined as police districts (n = 49). We linked Montreal livebirths 1997-2001 (n = 98 330) to police district crime measures, survey data on perceived security, and 2001 census data. We used multi-level analysis to calculate odds ratios (OR) for neighbourhood effects on SGA birth accounting for individual characteristics. Mothers residing in neighbourhoods with the most favourable perception had a lower odds of SGA birth than neighbourhoods with the least favourable perception [OR 0.87, 95% CI 0.77, 0.97]. Mothers in neighbourhoods with lower proportions of immigrants had lower odds of SGA birth relative to neighbourhoods with the highest proportion of immigrants. Reported crime, residential stability and material/social deprivation (accounting for neighbourhood perception) were not associated with SGA birth. Immigrant density and subjective perceptions of neighbourhood security are associated with SGA birth. Public health strategies to improve fetal growth should target neighbourhoods with low perceived security and high immigrant density.

Little is known about how birth outcomes vary in rural areas by degree of rural isolation. We conducted a retrospective cohort study of all births in Quebec, 1991-2000 to assess birth outcomes by the degree of rural isolation according to metropolitan influence as measured by work force commuting flows between rural and urban areas. Compared with urban areas, crude risks of preterm birth, small-for-gestational age birth, stillbirth, neonatal death and postneonatal death were similar in rural areas with strong metropolitan influence, but were significantly higher for preterm birth, stillbirth and postneonatal death in rural areas with weak or no metropolitan influence, and for neonatal death in rural areas with no metropolitan influence. Adjustment for maternal characteristics (age, mother tongue, education, marital status, parity, plurality and infant sex) attenuated the associations. The adjusted odds ratios [95% confidence intervals] were 1.36 [1.12, 1.64] for stillbirth in rural areas with weak metropolitan influence, 1.63 [1.14, 2.32] for neonatal death in rural areas with no metropolitan influence, 1.78 [1.21, 2.63] and 1.37 [1.07, 1.75] for postneonatal death in rural areas with weak and no metropolitan influence, respectively. Much higher neonatal death rates were observed for preterm or low-birthweight babies in rural areas with no metropolitan influence, suggesting inadequate access to optimal neonatal care. We conclude that birth outcomes in rural areas differ according to the degree of rural isolation. Fetuses and infants of mothers from rural areas with weak or no metropolitan influence are particularly vulnerable to the risks of death during the perinatal and postnatal periods.

Background The Maternal-Infant Research on Environmental Chemicals (MIREC) Study was established to obtain Canadian biomonitoring data for pregnant women and their infants, and to examine potential adverse health effects of prenatal exposure to priority environmental chemicals on pregnancy and infant health. Methods Women were recruited during the first trimester from 10 sites across Canada and were followed through delivery. Questionnaires were administered during pregnancy and post-delivery to collect information on demographics, occupation, life style, medical history, environmental exposures and diet. Information on the pregnancy and the infant was abstracted from medical charts. Maternal blood, urine, hair and breast milk, as well as cord blood and infant meconium, were collected and analysed for an extensive list of environmental biomarkers and nutrients. Additional biospecimens were stored in the study's Biobank. The MIREC Research Platform encompasses the main cohort study, the Biobank and follow-up studies. Results Of the 8716 women approached at early prenatal clinics, 5108 were eligible and 2001 agreed to participate (39%). MIREC participants tended to smoke less (5.9% vs. 10.5%), be older (mean 32.2 vs. 29.4 years) and have a higher education (62.3% vs. 35.1% with a university degree) than women giving birth in Canada. Conclusions The MIREC Study, while smaller in number of participants than several of the international cohort studies, has one of the most comprehensive datasets on prenatal exposure to multiple environmental chemicals. The biomonitoring data and biological specimen bank will make this research platform a significant resource for examining potential adverse health effects of prenatal exposure to environmental chemicals.

The investigation of heterogeneity remains an essential but difficult issue in the conduct of meta-analysis. We reviewed standard and graphical methods used to explore heterogeneity in meta-analysis and publications from January 2005 to April 2007 regarding meta-analyses that focused on perinatal health topics. We assessed their approaches to the investigation of heterogeneity, including: (1) whether statistical testing for heterogeneity was performed and, if so, which test was used, (2) how a finding of statistically significant heterogeneity was handled, and (3) how the analyses were conducted in the presence of heterogeneity.

Pre-eclampsia has been dubbed as 'a disease of primiparity'. However, the effects and mechanisms of the association of primiparity with pre-eclampsia have not been clearly defined. We conducted a systematic review of studies evaluating the effect of primiparity on the risk of pre-eclampsia, and studies (published between January 1966 and July 2005) on the mechanisms underlying such an association. A total of 26 original studies were identified and a meta-analysis carried out for the risk of pre-eclampsia among primiparous vs. multiparous women. Variably (1.4-5.5 times) higher risks of pre-eclampsia were observed in primiparous women in all studies, with a summary odds ratio (OR) of 2.42 [95% CI 2.16, 2.71]. The adjusted ORs were larger than crude ORs in all but one study after various adjustments. Except for abundant epidemiological evidence in support of the immune maladaptation theory, only four original studies examined the actual mechanisms of such primiparity-associated risk. Two (small) studies suggested differences in immunological responses in the aetiology of pre-eclampsia in primiparous vs. multiparous women. Two recent studies indicated that differences in angiogenic factor profile or reactivity to insulin resistance in early pregnancy may explain the elevated pre-eclampsia risk in first pregnancies. In conclusion, primiparity is associated with approximately 2.4-fold elevated risk of pre-eclampsia. Although immune maladaptation is generally considered as the basis to explain such an elevated risk, few data are available on immune maladaptation parameters in primiparous vs. multiparous pregnancies. Available data are insufficient to interpret the mechanisms of such primiparity-associated excess risk of pre-eclampsia.

Summary We used Statistics Canada's linked stillbirth, live birth and infant death files to assess the risks of adverse pregnancy outcomes among Inuit and North American Indian vs. other ethnic women in Quebec, 1985–97 (1 125 462 singleton births). Mother tongue was used to define ethnicity, with the largest French language group as the reference. Main outcome measures are adjusted odds ratios (AOR) for preterm birth, small-for-gestational-age (SGA), stillbirth, neonatal and postneonatal death controlled for maternal age, education, marital status, parity, infant sex, community size, and community-level random effects using multilevel logit models. Inuit women had higher risks of preterm birth (AOR = 1.49, 95% CI [1.25, 1.78]) and immaturity-related infant mortality (AOR = 3.03 [1.36, 6.74]), while Indian women did not. Infants of Inuit (AOR = 0.39 [0.31, 0.49]) and Indian (AOR = 0.27 [0.24, 0.31]) women had substantially lower risks of SGA. Elevated risks of stillbirth were observed among Indian women [AOR = 1.53 (1.09, 2.15)], and of postneonatal death among both Inuit (AOR = 4.45 [2.74, 7.22]) and Indian (AOR = 1.86 [1.28, 2.70]) infants. Both Inuit and Indian infants had much higher risks of sudden infant death syndrome (SIDS) and infection-related mortality. Although the absolute risks of adverse outcomes declined from 1985–87 to 1995–97, the relative disparities between aboriginal and non-aboriginal women changed little over this period. We conclude that Inuit and Indian women have different risk profiles for adverse pregnancy outcomes, and that prevention of preterm birth among Inuit women, and of SIDS and infection-related infant mortality in both aboriginal groups, are important targets for future research and intervention.