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Background: The assessment of birthweight for gestational age and the identification of small- and large-for-gestational age (SGA and LGA) infants remain contentious, despite the recent creation of the Intergrowth 21st Project and World Health Organisation (WHO) birthweight-for-gestational age standards., Objective: We carried out a study to identify birthweight-for-gestational age cut-offs, and corresponding population-based, Intergrowth 21st and WHO centiles associated with higher risks of adverse neonatal outcomes, and to evaluate their ability to predict serious neonatal morbidity and neonatal mortality (SNMM) at term gestation., Methods: The study population was based on non-anomalous, singleton live births between 37 and 41 weeks' gestation in the United States from 2003 to 2017. SNMM included 5-min Apgar score <4, neonatal seizures, need for assisted ventilation, and neonatal death. Birthweight-specific SNMM was modelled by gestational week using penalised B-splines. The birthweights at which SNMM odds were minimised (and higher by 10%, 50% and 100%) were estimated, and the corresponding population, Intergrowth 21st, and WHO centiles were identified. The clinical performance and population impact of these cut-offs for predicting SNMM were evaluated., Results: The study included 40,179,663 live births and 991,486 SNMM cases. Among female singletons at 39 weeks' gestation, SNMM odds was lowest at 3203 g birthweight, and 10% higher at 2835 g and 3685 g (population centiles 11th and 82nd, Intergrowth centiles 17th and 88th and WHO centiles 15th and 85th). Birthweight cut-offs were poor predictors of SNMM, for example, the cut-offs associated with 10% and 50% higher odds of SNMM among female singletons at 39 weeks' gestation resulted in a sensitivity, specificity, and population attributable fraction of 12.5%, 89.4%, and 2.1%, and 2.9%, 98.4% and 1.3%, respectively., Conclusions: Reference- and standard-based birthweight-for-gestational age indices and centiles perform poorly for predicting adverse neonatal outcomes in individual infants, and their associated population impact is also small., (© 2023 The Authors. Paediatric and Perinatal Epidemiology published by John Wiley & Sons Ltd.)

Background: The most important knowledge gap in connection with obstetric management for time of delivery in term low-risk pregnancies relates to the absence of information on long-term neurodevelopmental outcomes., Objectives: We examined risks of stillbirth, infant mortality, cerebral palsy (CP) and epilepsy among low-risk pregnancies., Methods: In this population-based Swedish study, we identified, from 1998 to 2019, 1,773,269 singleton infants born between 37 and 42 completed weeks in women with low-risk pregnancies. Poisson log-linear regression models were used to examine the association between gestational age at delivery and stillbirth, infant mortality, CP and epilepsy. Adjusted rate ratios (RR) and 95% confidence intervals expressing the effect of birth at a particular gestational week compared with birth at a later gestational week were estimated., Results: Compared with those born at a later gestation, RRs for stillbirth and infant mortality were higher among births at 37 weeks' and 38 weeks' gestation. The RRs for infant mortality were approximately 20% and 25% lower among births at 40 or 41 weeks compared with those born at later gestation, respectively. Infants born at 37 and 38 weeks also had higher RRs for CP (vs infants born at ≥38 and ≥39 weeks, respectively), while those born at 39 gestation had similar RRs (vs infants born at ≥40 weeks); infants born at 40 and 41 weeks had lower RRs of CP (vs those born at ≥41 and 42 weeks, respectively). The RRs for epilepsy were higher in those born at 37 and 38 weeks compared with those born at later gestation., Conclusions: Among low-risk pregnancies, birth at 37 or 38 completed weeks' gestation is associated with increased risks of stillbirth, infant mortality and neurological morbidity, while birth at 39-40 completed weeks is associated with reduced risks compared with births at later gestation., (© 2022 The Authors. Paediatric and Perinatal Epidemiology published by John Wiley & Sons Ltd.)

Background: Stillbirths are a major public health issue and a sensitive marker of the quality of care around pregnancy and birth. The UN Global Strategy for Women's, Children's and Adolescents' Health (2016-30) and the Every Newborn Action Plan (led by UNICEF and WHO) call for an end to preventable stillbirths. A first step to prevent stillbirths is obtaining standardised measurement of stillbirth rates across countries. We estimated stillbirth rates and their trends for 195 countries from 2000 to 2019 and assessed progress over time., Methods: For a systematic assessment, we created a dataset of 2833 country-year datapoints from 171 countries relevant to stillbirth rates, including data from registration and health information systems, household-based surveys, and population-based studies. After data quality assessment and exclusions, we used 1531 datapoints to estimate country-specific stillbirth rates for 195 countries from 2000 to 2019 using a Bayesian hierarchical temporal sparse regression model, according to a definition of stillbirth of at least 28 weeks' gestational age. Our model combined covariates with a temporal smoothing process such that estimates were informed by data for country-periods with high quality data, while being based on covariates for country-periods with little or no data on stillbirth rates. Bias and additional uncertainty associated with observations based on alternative stillbirth definitions and source types, and observations that were subject to non-sampling errors, were included in the model. We compared the estimated stillbirth rates and trends to previously reported mortality estimates in children younger than 5 years., Findings: Globally in 2019, an estimated 2·0 million babies (90% uncertainty interval [UI] 1·9-2·2) were stillborn at 28 weeks or more of gestation, with a global stillbirth rate of 13·9 stillbirths (90% UI 13·5-15·4) per 1000 total births. Stillbirth rates in 2019 varied widely across regions, from 22·8 stillbirths (19·8-27·7) per 1000 total births in west and central Africa to 2·9 (2·7-3·0) in western Europe. After west and central Africa, eastern and southern Africa and south Asia had the second and third highest stillbirth rates in 2019. The global annual rate of reduction in stillbirth rate was estimated at 2·3% (90% UI 1·7-2·7) from 2000 to 2019, which was lower than the 2·9% (2·5-3·2) annual rate of reduction in neonatal mortality rate (for neonates aged <28 days) and the 4·3% (3·8-4·7) annual rate of reduction in mortality rate among children aged 1-59 months during the same period. Based on the lower bound of the 90% UIs, 114 countries had an estimated decrease in stillbirth rate since 2000, with four countries having a decrease of at least 50·0%, 28 having a decrease of 25·0-49·9%, 50 having a decrease of 10·0-24·9%, and 32 having a decrease of less than 10·0%. For the remaining 81 countries, we found no decrease in stillbirth rate since 2000. Of these countries, 34 were in sub-Saharan Africa, 16 were in east Asia and the Pacific, and 15 were in Latin America and the Caribbean., Interpretation: Progress in reducing the rate of stillbirths has been slow compared with decreases in the mortality rate of children younger than 5 years. Accelerated improvements are most needed in the regions and countries with high stillbirth rates, particularly in sub-Saharan Africa. Future prevention of stillbirths needs increased efforts to raise public awareness, improve data collection, assess progress, and understand public health priorities locally, all of which require investment., Funding: Bill & Melinda Gates Foundation and the UK Foreign, Commonwealth and Development Office., Competing Interests: Declaration of interests We declare no competing interests., (Copyright © 2021 World Health Organization; licensee Elsevier. This is an Open Access article published under the CC BY 3.0 IGO license which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In any use of this article, there should be no suggestion that WHO endorses any specific organisation, products or services. The use of the WHO logo is not permitted. This notice should be preserved along with the article's original URL.)

Objective: To evaluate the performance of the INTERGROWTH-21st Project newborn standard vis-a-vis the current Canadian birth weight-for-gestational age reference., Methods: All hospital-based singleton live births in Canada (excluding Quebec) between 2002 and 2012 with a gestational age between 33 and 42 weeks were included using information obtained from the Canadian Institute for Health Information. Small- and large-for gestational age centile categories of the INTERGROWTH standard and Canadian reference were contrasted in terms of frequency distributions and rates of composite neonatal morbidity/mortality., Results: Among 2,753,817 singleton live births, 0.87% and 9.63% were <3rd centile and >97th centile, respectively, of the INTERGROWTH standard, while 2.27% and 3.55% were <3rd centile and >97th centile, respectively, of the Canadian reference. Infants <3rd centile and >97th centile had a composite neonatal morbidity/mortality rate of 46.4 and 12.9 per 1,000 live births, respectively, under the INTERGROWTH standard and 30.9 and 16.6 per 1,000 live births, respectively, under the Canadian reference. The INTERGROWTH standard <3rd centile and >97th centile categories had detection rates of 3.14% and 9.74%, respectively, for composite neonatal morbidity/ mortality compared with 5.48% and 4.60%, respectively for the Canadian reference. Similar patterns were evident in high- and low-risk subpopulations., Conclusions: The centile distribution of the INTERGROWTH newborn standard is left shifted compared with the Canadian reference, and this shift alters the frequencies and neonatal morbidity/mortality rates associated with specific centile categories. Further outcome-based research is required for defining abnormal growth categories before the INTERGROWTH newborn standard can be used.

Background: The Twin Birth Study randomized women with uncomplicated pregnancies, between 32(0/7)-38(6/7) weeks' gestation where the first twin was in cephalic presentation, to a policy of either a planned cesarean or planned vaginal delivery. The primary analysis showed that planned cesarean delivery did not increase or decrease the risk of fetal/neonatal death or serious neonatal morbidity as compared with planned vaginal delivery., Objective: This study presents the secondary outcome of death or neurodevelopmental delay at 2 years of age., Study Design: A total of 4603 children from the initial cohort of 5565 fetuses/infants (83%) contributed to the outcome of death or neurodevelopmental delay. Surviving children were screened using the Ages and Stages Questionnaire with abnormal scores validated by a clinical neurodevelopmental assessment. The effect of planned cesarean vs planned vaginal delivery on death or neurodevelopmental delay was quantified using a logistic model to control for stratification variables and using generalized estimating equations to account for the nonindependence of twin births., Results: Baseline maternal, pregnancy, and infant characteristics were similar. Mean age at assessment was 26 months. There was no significant difference in the outcome of death or neurodevelopmental delay: 5.99% in the planned cesarean vs 5.83% in the planned vaginal delivery group (odds ratio, 1.04; 95% confidence interval, 0.77-1.41; P = .79)., Conclusion: A policy of planned cesarean delivery provides no benefit to children at 2 years of age compared with a policy of planned vaginal delivery in uncomplicated twin pregnancies between 32(0/7)-38(6/7)weeks' gestation where the first twin is in cephalic presentation., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Variation in birth registration criteria may compromise international comparisons of fetal and infant mortality. We examined the effect of birth registration practices on fetal and infant mortality rates to determine whether observed differences in perinatal and infant mortality rates were artifacts of birth registration or reflected true differences in health status., Methods: A retrospective population-based cohort study was done using data from Canada, United States, Denmark, Finland, Iceland, Norway, and Sweden from 1995-2005. Main outcome measures included live births by gestational age and birth weight; gestational age-and birth weight-specific stillbirth rates; neonatal, post-neonatal, and cause-specific infant mortality., Results: Proportion of live births <22 weeks varied substantially: Sweden (not reported), Iceland (0.00%), Finland (0.001%), Denmark (0.01%), Norway (0.02%), Canada (0.07%) and United States (0.08%). At 22-23 weeks, neonatal mortality rates were highest in Canada (892.2 per 1000 live births), Denmark (879.3) and Iceland (1000.0), moderately high in the United States (724.1), Finland (794.3) and Norway (739.0) and low in Sweden (561.2). Stillbirth:live birth ratios at 22-23 weeks were significantly lower in the United States (79.2 stillbirths per 100 live births) and Finland (90.8) than in Canada (112.1), Iceland (176.2) and Norway (173.9). Crude neonatal mortality rates were 83% higher in Canada and 96% higher in the United States than Finland. Neonatal mortality rates among live births ≥ 28 weeks were lower in Canada and United States compared with Finland. Post-neonatal mortality rates were higher in Canada and United States than in Nordic countries., Conclusions: Live birth frequencies and stillbirth and neonatal mortality patterns at the borderline of viability are likely due to differences in birth registration practices, although true differences in maternal, fetal and infant health cannot be ruled out. This study emphasises the need for further standardisations, in order to enhance the relevance of international comparisons of infant mortality.

Background: Recent studies have shown that older mothers who deliver at preterm gestation have lower neonatal mortality rates compared with younger mothers who deliver at preterm gestation. We examined the effect of maternal age on gestational age-specific perinatal mortality., Methods: We compared fetal, neonatal and perinatal mortality rates among singleton births in the United States, 2003-2005, to mothers aged ≥35 versus 20-29 years. The analysis was stratified by gestational age and perinatal mortality rates were contrasted by maternal age at earlier (22-33 weeks) and later gestation (≥34 weeks). Gestational age-specific perinatal mortality rates were calculated using the traditional perinatal formulation (deaths among births at any gestation divided by total births at that gestation) and also the fetuses-at-risk model (deaths among births at any gestation divided by fetuses-at-risk of death at that gestation).Logistic regression was used to estimate adjusted odds ratios (AOR) for perinatal death., Results: Under the traditional approach, fetal death rates at 22-33 weeks were non-significantly lower among older mothers (AOR 0.97, 95% confidence interval [CI] 0.91-1.03), while rates were significantly higher among older mothers at ≥34 weeks (AOR 1.66, 95% CI 1.56-1.76). Neonatal death rates were significantly lower among older compared with younger mothers at 22-33 weeks (AOR=0.93, 95% CI 0.88-0.98) but higher at ≥34 weeks (AOR 1.26, 95% CI 1.21-1.31). Under the fetuses-at-risk model, both rates were higher among older vs younger mothers at early gestation (AOR for fetal and neonatal mortality 1.35, 95% CI 1.27-1.43 and 1.31, 95% CI 1.24-1.38, respectively) and late gestation (AOR for fetal and neonatal mortality 1.66, 95% CI 1.56-1.76) and 1.21, 95% CI 1.14-1.29, respectively)., Conclusions: Although the traditional prognostic perspective on the risk of perinatal death among older versus younger mothers varies by gestational age at birth, the causal fetuses-at-risk model reveals a consistently elevated risk of perinatal death at all gestational ages among older mothers.

Objective: To examine international rates of preterm birth and potential associations with stillbirths and neonatal deaths at late preterm and term gestation., Design: Ecological study., Setting: Canada, USA and 26 countries in Europe., Population: All deliveries in 2004., Methods: Information on preterm birth (<37, 32-36, 28-31 and 24-27 weeks of gestation) and perinatal deaths was obtained for 28 countries. Data sources included files and publications from Statistics Canada, the EURO-PERISTAT project and the National Center for Health Statistics. Pearson correlation coefficients and random-intercept Poisson regression were used to examine the association between preterm birth rates and gestational age-specific stillbirth and neonatal death rates. Rate ratios with 95% confidence intervals were estimated after adjustment for maternal age, parity and multiple births., Main Outcome Measures: Stillbirths and neonatal deaths ≥ 32 and ≥ 37 weeks of gestation., Results: International rates of preterm birth (<37 weeks) ranged between 5.3 and 11.4 per 100 live births. Preterm birth rates at 32-36 weeks were inversely associated with stillbirths at ≥ 32 weeks (adjusted rate ratio 0.94, 95% CI 0.92-0.96) and ≥ 37 weeks (adjusted rate ratio 0.88, 95% CI 0.85-0.91) of gestation and inversely associated with neonatal deaths at ≥ 32 weeks (adjusted rate ratio 0.88, 95% CI 0.85-0.91) and ≥ 37 weeks (adjusted rate ratio 0.82, 95% CI 0.78-0.86) of gestation., Conclusions: Countries with high rates of preterm birth at 32-36 weeks of gestation have lower stillbirth and neonatal death rates at and beyond 32 weeks of gestation. Contemporary rates of preterm birth are indicators of both perinatal health and obstetric care services., (© 2012 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2012 RCOG.)

Objectives: To examine variations in the registration of extremely low birthweight and early gestation births and to assess their effect on perinatal and infant mortality rankings of industrialised countries., Design: Retrospective population based study., Setting: Australia, Canada, European countries, and the United States for 2004; Australia, Canada, and New Zealand for 2007., Population: National data on live births and on fetal, neonatal, and infant deaths., Main Outcome Measures: Reported proportions of live births with birth weight/gestational age of less than 500 g, less than 1000 g, less than 24 weeks, and less than 28 weeks; crude rates of fetal, neonatal, and infant mortality; mortality rates calculated after exclusion of births under 500 g, under 1000 g, less than 24 weeks, and less than 28 weeks., Results: The proportion of live births under 500 g varied widely from less than 1 per 10,000 live births in Belgium and Ireland to 10.8 per 10,000 live births in Canada and 16.9 in the United States. Neonatal deaths under 500 g, as a proportion of all neonatal deaths, also ranged from less than 1% in countries such as Luxembourg and Malta to 29.6% in Canada and 31.1% in the United States. Rankings of countries based on crude fetal, neonatal, and infant mortality rates differed substantially from rankings based on rates calculated after exclusion of births with a birth weight of less than 1000 g or a gestational age of less than 28 weeks., Conclusions: International differences in reported rates of extremely low birthweight and very early gestation births probably reflect variations in registration of births and compromise the validity of international rankings of perinatal and infant mortality.

Background: Infant mortality rates are higher in the United States than in Canada. We explored this difference by comparing gestational age distributions and gestational age-specific mortality rates in the two countries., Methods: Stillbirth and infant mortality rates were compared for singleton births at >or=22 weeks and newborns weighing>or=500 g in the United States and Canada (1996-2000). Since menstrual-based gestational age appears to misclassify gestational duration and overestimate both preterm and postterm birth rates, and because a clinical estimate of gestation is the only available measure of gestational age in Canada, all comparisons were based on the clinical estimate. Data for California were excluded because they lacked a clinical estimate. Gestational age-specific comparisons were based on the foetuses-at-risk approach., Results: The overall stillbirth rate in the United States (37.9 per 10,000 births) was similar to that in Canada (38.2 per 10,000 births), while the overall infant mortality rate was 23% (95% CI 19-26%) higher (50.8 vs 41.4 per 10,000 births, respectively). The gestational age distribution was left-shifted in the United States relative to Canada; consequently, preterm birth rates were 8.0 and 6.0%, respectively. Stillbirth and early neonatal mortality rates in the United States were lower at term gestation only. However, gestational age-specific late neonatal, post-neonatal and infant mortality rates were higher in the United States at virtually every gestation. The overall stillbirth rates (per 10,000 foetuses at risk) among Blacks and Whites in the United States, and in Canada were 59.6, 35.0 and 38.3, respectively, whereas the corresponding infant mortality rates were 85.6, 49.7 and 42.2, respectively., Conclusions: Differences in gestational age distributions and in gestational age-specific stillbirth and infant mortality in the United States and Canada underscore substantial differences in healthcare services, population health status and health policy between the two neighbouring countries.

Contemporary fetal growth standards are created by using theoretical properties (percentiles) of birth weight (for gestational age) distributions. The authors used a clinically relevant, outcome-based methodology to determine if separate fetal growth standards are required for singletons and twins. All singleton and twin livebirths between 36 and 42 weeks' gestation in the United States (1995-2002) were included, after exclusions for missing information and other factors (n = 17,811,922). A birth weight range was identified, at each gestational age, over which serious neonatal morbidity and neonatal mortality rates were lowest. Among singleton males at 40 weeks, serious neonatal morbidity/mortality rates were lowest between 3,012 g (95% confidence interval (CI): 3,008, 3,018) and 3,978 g (95% CI: 3,976, 3,980). The low end of this optimal birth weight range for females was 37 g (95% CI: 21, 53) less. The low optimal birth weight was 152 g (95% CI: 121, 183) less for twins compared with singletons. No differences were observed in low optimal birth weight by period (1999-2002 vs. 1995-1998), but small differences were observed for maternal education, race, parity, age, and smoking status. Patterns of birth weight-specific serious neonatal morbidity/neonatal mortality support the need for plurality-specific fetal growth standards.

Background: Although national health insurance plans and social programs introduced in the 1960s led to reductions in regional disparities in infant mortality in Canada, it is unclear if such patterns prevailed in the 1990s when the health care and related systems were under fiscal duress. This study examined regional patterns of change in infant mortality in Canada in recent decades., Methods: We analysed regional changes in crude infant mortality rates and in infant mortality rates among live births with a birth weight >or= 500 g and >or= 1,000 g in Canada from 1945 to 2002. Associations between baseline infant mortality rates in the provinces and territories (e.g., in 1985-89) and the change observed in infant mortality rates over the subsequent period (e.g., between 1985-89 and 1995-99) were assessed using Spearman's rank correlation coefficient. Trends in regional disparities were also assessed by calculating period-specific rate ratios between provinces/territories with the highest versus the lowest infant mortality., Results: Provincial/territorial infant mortality rates in 1945-49 were not correlated with changes in infant mortality over the next 10 years (rho = 0.01, P = 0.99). However, there was a strong negative correlation between infant mortality rates in 1965-69 and the subsequent decline in infant mortality (rho = - 0.85, P = 0.002). Provinces/territories with higher infant mortality rates in 1965-69 (Northwest Territories 64.7 vs British Columbia 20.7 per 1,000 live births) experienced relatively larger reductions in infant mortality between 1965-69 and 1975-79 (53.7% decline in the Northwest Territories vs a 36.6% decline in British Columbia). This pattern was reversed in the more recent decades. Provinces/territories with higher infant mortality rates >or= 500 g in 1985-89 experience relatively smaller reductions in infant mortality between 1985-89 and 2000-02 (rho = 0.82, P = 0.004). The infant mortality >or= 500 g rate ratio (contrasting the province/territory with the highest versus lowest infant mortality) was 3.2 in 1965-69, 2.4 in 1975-79, 2.2 in 1985-89, 3.1 in 1995-99 and 4.1 in 2000-02., Conclusion: Fiscal constraints in the 1990s led to a reversal of provincial/territorial patterns of change in infant mortality in Canada and to an increase in regional health disparities.

Objectives: To examine whether the smaller size of infants born to primiparous, short, or thin mothers is associated with increased risks of perinatal mortality., Study Design: We compared gestational age-specific patterns of "revealed" small-for-gestational-age (SGA) birth (number of SGA births expressed as a proportion of fetuses remaining in utero at each gestational age) with the patterns for perinatal mortality among singleton late fetal deaths and live births (n = 791,523) to Swedish mothers in 1992 to 2001., Results: Based on a single standard for SGA, primiparae were at substantially higher risk of revealed SGA throughout gestation, paralleling the pattern for perinatal mortality. However, for short and thin women, risks of revealed SGA were much more consistent with those for perinatal mortality when SGA was based on height-specific or body mass index-specific standards, respectively, rather than on the single standard. Overweight and obese mothers had lower revealed SGA rates based on either standard but higher perinatal mortality rates., Conclusions: Slower fetal growth due to maternal short stature or low prepregnancy body mass index appears to be physiologic, whereas the slower growth of fetuses born to primiparous women is associated with higher risks of perinatal death.

Objective: The objective of this study was to critically examine potential artifacts and biases underlying the use of 'customised' standards of birthweight for gestational age (GA)., Design: Population-based cohort study., Setting: Sweden., Population: A total of 782,303 singletons > or =28 weeks of gestation born in 1992-2001 to Nordic mothers with complete data on birthweight; GA; and maternal age, parity, height, and pre-pregnancy weight., Methods: We compared perinatal mortality in four groups of infants based on the following classification of small for gestational age (SGA): non-SGA based on either population-based or customised standards (the reference group), SGA based on the population-based standard only, SGA based on the customised standard only, and SGA according to both standards. We used graphical methods to compare GA-specific birthweight cutoffs for SGA using the two standards and also used logistic regression to control for differences in GA and maternal pre-pregnancy body mass index (BMI) in the four groups., Main Outcome Measures: Perinatal mortality, including stillbirth and neonatal death., Results: Customisation led to a large artifactual increase in the proportion of SGA infants born preterm. Adjustment for differences in GA and maternal BMI markedly reduced the excess risk among infants classified as SGA by customised standards only., Conclusion: The large increase in perinatal mortality risk among infants classified as SGA based on customised standards is largely an artifact due to inclusion of more preterm births.

Objective: To identify potential determinants of perinatal mortality and neonatal morbidity among second twins relative to first twins., Methods: A retrospective cohort design was used to study twin deliveries in Nova Scotia from 1988 to 2002. Monoamniotic or conjoined twins and twin pairs with major congenital anomaly or antepartum fetal death of either twin were excluded. The primary outcome was a composite measure of perinatal mortality and neonatal morbidity, including birth asphyxia, respiratory distress, neonatal trauma, and infection. Risk of adverse outcome of second twins relative to first-born co-twins was determined by matched-pair analysis., Results: Of 1,542 twin pairs, the second twin was at greater risk of composite adverse outcome (relative risk [RR] 1.62, 95% confidence interval [CI] 1.38-1.9) than the first twin. This excess risk was evident independent of presentation, chorionicity, or infant sex but was associated with planned vaginal delivery, birth weight discordance, and prolonged interdelivery interval. Term second twins were less likely to suffer excess morbidity with elective cesarean (RR 1.0, 95% CI 0.14-7.10) than with planned vaginal delivery (RR 3.0, 95% CI 1.47-6.11). The major contributors to neonatal morbidity in the second twin were birth asphyxia at 37 weeks or later and respiratory distress syndrome at less than 37 weeks., Conclusion: The second twin is at greater risk of adverse perinatal outcome than the first twin, independent of presentation, chorionicity, or infant sex. Planned vaginal delivery, birth weight discordance, and prolonged interdelivery interval increase this infant risk. Elective cesarean delivery at term may improve perinatal outcome for the second twin. However, the number of cesarean births required to prevent one case of composite adverse outcome, assuming causality, was 33.

Low birthweight (LBW) is highly associated with death during infancy, and countries with the highest LBW rates also have the highest infant mortality rates. We compared temporal trends in LBW with both overall and birthweight-specific infant mortality in United States, Canada, Argentina, Chile, and Uruguay over two time periods, using cohort and cross-sectional analysis of national population-based vital statistics for 1985-89 and 1995-98. Infant mortality diminished substantially (RR = 0.60-0.80 for the later vs. earlier periods) and to a similar degree in all birthweight categories in all five study countries, despite an increase in LBW in the US and Uruguay, minimal changes in Canada and Argentina, and a decrease in Chile. The strength of the (positive) association between LBW and overall infant mortality diminished over the two time periods (from r(s) = +0.80 to +0.25 and RR per SD increase in LBW rate from 2.13 [2.09, 2.17] to 1.76 [1.74, 1.79]). The proportion of infant deaths occurring among LBW infants was negatively correlated with overall infant mortality in both time periods (r(s) = -0.30 and -0.60, RR = 0.68 [0.67, 0.68] and 0.47 [0.46, 0.47]). Developed and less developed countries in the Americas have succeeded in reducing infant mortality in all birthweight groups despite inconsistent changes in LBW rates, and none has achieved this success primarily by reducing LBW. Although our results are not necessarily generalisable to the least developed countries in South Asia and sub-Saharan Africa, it is likely that all countries can substantially reduce their infant mortality rates by improving the care of infants at normal and low birthweights.

Objective: We examined trends in twin preterm birth <37 weeks following ruptured membranes (ROM), medically indicated preterm birth, and preterm birth following spontaneous onset of labor (PTL). We further examined whether the changes in preterm birth subtypes were associated with trends in twin perinatal mortality., Study Design: We carried out a retrospective cohort study of 1,172,405 twin live births and stillbirths delivered in the US between 1989 and 2000. Trends in preterm birth subtypes and perinatal mortality (stillbirths at > or = 22 weeks plus neonatal deaths within 28 days) were examined through ecological logistic regression models after adjusting for confounders., Results: Twin preterm birth among whites increased from 46.6% in 1989 to 1990 to 56.7% in 1999 to 2000, and from 56.1% to 61.0% among blacks over the same period. Medically indicated preterm birth increased by 50% (95% CI 49-52) among whites, and by 33% (95% CI 29-36) among blacks. PTL increased by 24% among whites, but remained fairly unchanged among blacks between the two periods. Preterm birth following ROM also did not change between the 2 periods among whites, but declined by 7% among blacks. Perinatal mortality among twin births declined by 41% (95% CI 38-44) among whites, and by 37% (95% CI 32-42) among blacks between 1989 and 1990 and 1999 and 2000. This mortality decline was most closely associated with the increase in medically indicated preterm birth among whites, and with the decrease in preterm birth following ROM among blacks., Conclusion: Temporal trends in twin preterm birth varied substantially based on underlying subtypes and race. The increase in medically indicated preterm birth is associated with a large reduction in perinatal mortality.

The purpose of this study was to examine the association between intrapair birthweight discordance and fetal and neonatal mortality. This was a historical cohort study, using the Statistics Canada linked birth-infant death file. Twin births in Canada (excluding Ontario) for the period 1986-1997 were studied. Outcome measures were fetal and neonatal mortality. Among 59,034 twin births, 53% had 0 to 9% birthweight difference; 30% had 10 to 19% discordance; 11% had 20 to 29% discordance; and 6% had > or = 30% discordance. Maternal age, parity, sex discordance, and gestational age were important factors affecting birth weight discordance. Fetal death rates were 0.95, 1.26, 3.14, and 11.10%, respectively, in infants with a birthweight discordance of 0 to 9, 10 to 19, 20 to 29, and > or = 30%. Corresponding figures for neonatal death rates were 1.90, 2.32, 3.05, and 8.86%, respectively. Adjustment for important confounding variables including the actual birthweight and gestational age substantially reduced the birthweight discordance-related risk of fetal and neonatal mortality, but the results remained statistically significant and clinically important. The birthweight discordance-related risk of fetal and neonatal mortality was higher in smaller twins than in larger twins and higher in infants with gestational age > or = 37 weeks than those < 37 weeks. Birthweight discordance is an important risk factor for fetal and neonatal mortality, and the birthweight discordance-related risk of fetal and neonatal mortality is higher in smaller twins than in larger twins and higher in term twins than in preterm twins.

Objective: Despite the recent increase in preterm birth in the United States, trends in preterm birth subtypes have not been adequately examined. We examined trends in preterm birth among singletons following ruptured membranes, medical indications, and spontaneous preterm birth and evaluated the impact of these trends on perinatal mortality., Methods: A population-based, retrospective cohort study comprising 46,375,578 women (16% blacks) who delivered singleton births in the United States, 1989 through 2000, was performed. Rates of preterm birth (< 37 weeks), their subtypes, and associated perinatal mortality (stillbirths at >/= 22 weeks plus neonatal deaths within 28 days), before and after adjustment for potential confounders, were derived from ecological logistic regression models., Results: Preterm birth rates increased by 14% (95% confidence interval 13-15%) among whites from 8.3% to 9.4% and decreased by 15% (95% confidence interval 14-16%) among blacks from 18.5% to 16.2% between 1989 and 2000. Among whites, preterm birth following ruptured membranes declined by 23%, medically indicated preterm birth increased by 55%, and spontaneous preterm birth increased by 3%. Among blacks, preterm birth following ruptured membranes declined by 37%, medically indicated preterm birth increased by 32%, and spontaneous preterm birth decreased by 27%. The largest decline in perinatal mortality among whites was associated with increases in medically indicated preterm birth, whereas the largest decline in perinatal mortality among blacks was associated with declines in preterm birth following ruptured membranes and spontaneous preterm birth., Conclusion: Temporal trends in preterm birth varied substantially based on underlying subtype and maternal race. The recent increase in medically indicated preterm birth was associated with a favorable reduction in perinatal mortality.

Background: Traditional perinatal epidemiology appears to embrace fallacious concepts of risk. The use of incorrect denominators for perinatal rates is commonplace both for straightforward indices such as the gestational age-specific labor induction rate and also for the more conceptually challenging indices such as the gestational age-specific neonatal mortality rate. As a consequence, perinatology is beset by several conondrums including the paradox of intersecting perinatal mortality curves. PROPOSITION: These traditions are ideally replaced by alternative concepts that may be derived a priori and measured using indices such as presented here: the incidence of birth (i.e., the gestational age-specific birth rate), the incidence of growth restriction (i.e., the gestational age-specific growth-restriction rate) and the incidence of death (i.e., the age-specific mortality rate)., Results: The incidence of birth, growth restriction, and death quantify the core phenomena in perinatology and reveal congruent and coherent patterns of occurrence., Conclusions: These new indices can free perinatal epidemiology from erroneous concepts of risk and resolve the paradoxal phenomena that plague the perinatal domain. They also permit the development of a theoretical framework for obstetric intervention, which in recent years has been based exclusively on empirical evidence.

Birth-weight- and gestational-age-specific perinatal mortality curves intersect when compared by race and maternal smoking. The authors propose a new measure to replace fetal and infant mortality and an analytic strategy to assess the effects of risk factors on this outcome. They used 1998 data for US Blacks and Whites. Age-specific post-last menstrual period (LMP) mortality rate was defined as the proportion of deaths (stillbirth, perinatal death, or infant death) at a given age post-LMP. The authors used extended Cox regression with time-varying covariates and hazard ratios to model the effects of race and smoking on post-LMP mortality. Perinatal mortality rates (conventional calculation) for Blacks and Whites showed the expected crossover. However, analyses of post-LMP mortality showed no crossover. For the Black-White comparison, a hazard ratio of 1.72 (95% confidence interval: 1.67, 1.77) was obtained. The hazard was higher for smokers than for nonsmokers, but the hazard ratio increased from 1.09 (95% confidence interval: 0.98, 1.22) at 22 weeks to 1.82 (95% confidence interval: 1.72, 1.92) at 40 weeks. The hazard ratio associated with birth was also time dependent: higher than 1 for preterm gestation and lower than 1 for term gestation. The increasing adverse effect of smoking with gestational age suggests an accumulating effect of smoking on mortality. Modeling post-LMP mortality eliminates the crossover paradox for race and maternal smoking in a single statistical model.

Objective: We sought to evaluate the contributions of changes in birth registration, labor induction, and cesarean delivery on trends in twin neonatal mortality rates., Study Design: We conducted a population-based, retrospective cohort study of twin live births, using linked birth-infant death data in the United States (1989-1999). Relative risks and 95% confidence intervals that quantified changes in neonatal (0-27 days) mortality rates were derived from ecologic logistic regression models that were fit after aggregation of the data by each state in the United States., Results: The frequency of live born twins who weighed <500 g increased 72%, from 0.7% in 1989 to 1.2% in 1999, of live born twins who weighed 500 to 749 g and 750 to 999 g increased by 55% and 28%, respectively, between 1989 and 1999. Preterm birth rates increased by 19%, from 46.2% in 1989 to 57.2% in 1999. The rate of labor induction increased from 5.8% to 13.9%, and the cesarean delivery rate increased from 49.8% to 56.3%. Between 1989 to 1991 and 1997 to 1999, the crude neonatal mortality rates among twins who weighed >or=500 g declined by 37% (95% CI, 35%-40%) from 21.5 to 13.6 per 1000 twin live births. Adjustments for preterm labor induction, preterm cesarean delivery, term labor induction, term cesarean delivery, and sociodemographic factors had little influence on neonatal mortality rate trends., Conclusion: Increases in preterm birth because of obstetric intervention among twins have not led to increases in twin neonatal mortality rates in the United States.

Since the midtwentieth century, stillbirths (late fetal deaths) and early neonatal deaths have often been combined into a single category of "perinatal" deaths. In the past, such a combination was justified by the fact that asphyxia was a common cause of death during labor (intrapartum stillbirth) and shortly after birth and by geographic and temporal differences in classification of livebirths versus stillbirths. In more recent years, however, the etiologic determinants have diverged sharply, with many fewer early neonatal deaths caused by asphyxia and relatively many more caused by congenital anomalies. Moreover, the increasingly common stratification of pregnancy outcome measures by gestational age or birth weight leads to the use of an inappropriate denominator (total livebirths plus stillbirths within each gestational age or birth weight category) for denoting risk for the stillbirth component, because all unborn fetuses (including the majority of those not born within the specified gestational age or birth weight range) are at risk of being stillborn in that range. The authors suggest that, whenever possible, stillbirths and early neonatal deaths should be reported separately, with gestational age-specific risks of stillbirth based on all fetuses at risk, and that antepartum and intrapartum stillbirths be reported separately.

Understanding the causes that underlie the recent dramatic declines in infant deaths caused by congenital anomalies requires an appreciation of trends in cause-specific infant mortality, and especially trends in gestational age-specific and cause-specific fetal mortality. This article examines temporal changes in gestational age-specific and cause-of-death-specific fetal mortality rates in Canada, congenital anomaly-related infant mortality rates in Canada, England and Wales, and the United States, and cause-of-death-specific infant mortality rates in Canada and the United States. Fetal deaths caused by congenital anomalies at very early gestation (20-25 weeks) have increased dramatically in recent years, while fetal and infant deaths at later gestations have declined. Prenatal diagnosis and selective termination of pregnancies affected by congenital anomalies appears to be the major factor responsible for the accelerated decline in infant deaths. Further declines in overall infant mortality in industrialized countries can be expected as a result of an increasing uptake of prenatal diagnosis.

Despite widespread recognition that preventing preterm birth is the most important perinatal challenge facing industrialized countries, preterm birth has increased steadily in recent years. This article examines the relation between trends in preterm birth, preterm labor induction/cesarean delivery, stillbirth, and infant mortality. The recent rise in preterm birth in the United States and Canada has been mainly due to increases in mild preterm birth (34-36 weeks). Live births at 34 to 36 weeks' gestation have increased largely as a consequence of increases in preterm induction and preterm cesarean delivery among women at high risk for adverse pregnancy outcomes. Increased obstetric intervention at 34 to 36 weeks' gestation appears to have led to larger-than-expected temporal declines in stillbirth rates at this gestation. Infant mortality rates have declined overall and also among live births at 34 to 36 weeks' gestation. Obstetric intervention at preterm gestation, when indicated, can prevent stillbirth and reduce infant morbidity and mortality despite the increasing rates of preterm delivery.

Recent increases in the frequency of multiple births and simultaneous increases in preterm birth among multiple births have focused attention on such births. However, most previous studies have examined twins rather than higher-order multiples. We carried out a study to examine rates and trends in preterm birth and in gestational age-specific fetal and infant mortality among triplet births in Canada. We used data from the stillbirth, live birth and mortality files of Statistics Canada for the years 1985-97. All births in Canada (excluding those occurring in Ontario and Newfoundland) were included in the study, with two periods (1985-90 vs. 1991-96) being contrasted for assessing temporal change. Changes were estimated using relative risks, 95 confidence intervals [CI] and two-tailed P-values. The rate of preterm birth among triplet live births increased by 6 (95 CI 3, 9) from 90.4 in 1985-90 to 96.0 in 1991-96. Stillbirth rates among triplets did not change significantly and were 30.3 per 1000 total births in 1985-90 and 33.8 per 1000 total births in 1991-96. Infant mortality among triplets declined from 112.7 per 1000 live births in 1985-90 to 73.8 per 1000 live births in 1991-96. In spite of temporal reductions in infant mortality, triplet births continue to be associated with very high rates of preterm birth and fetal and infant mortality. Fetal mortality among triplets has not changed over the last ten years.

Context: Prenatal diagnosis and termination of affected pregnancies can prevent infant deaths due to congenital anomalies, but an effect at the population level has not been shown., Objective: To examine the impact of recent changes in congenital anomaly-related fetal and infant deaths on overall population-based infant mortality., Design, Setting, and Subjects: Birth cohort-based study of all live births, stillbirths, and infant deaths in Canada (excluding Ontario) for 1991-1998., Main Outcome Measures: Cause-specific infant mortality rates and gestational age-specific fetal death rates., Results: The birth cohort-based infant mortality rate fluctuated between 6.4 and 6.1 per 1000 live births between 1991 and 1995, then dropped to 5.4 per 1000 in 1996 and 5.5 per 1000 in 1997. The rate of infant death from congenital anomalies was stable between 1991 and 1995 but declined by 21% (95% confidence interval, 19%-32%) from 1.86 per 1000 in 1995 to 1.47 per 1000 in 1996 and 1997. Fetal deaths due to pregnancy termination at 20 to 23 weeks' gestation increased dramatically in 1994, while fetal deaths due to congenital anomalies at 20 to 21 weeks increased in 1995 and subsequently. Provinces/territories with high rates of fetal death due to pregnancy termination/congenital anomalies at 20 to 23 weeks had fewer infant deaths due to congenital anomalies., Conclusion: A large decrease in infant deaths due to congenital anomalies was associated with the most recent decline in infant mortality in Canada, suggesting that increases in prenatal diagnosis and pregnancy termination for congenital anomalies are related to decreases in overall infant mortality at the population level.

Prenatal diagnosis of major congenital anomalies and subsequent termination of affected pregnancies has been widely available as part of routine obstetric care in recent years. In this study, vital statistical data on stillbirths, live births, and infant deaths were used to examine secular trends in gestational age-specific and category-specific fetal and infant mortality due to congenital anomalies in Canada (excluding Ontario and Newfoundland) from 1985-1996. Comparisons of the rates between 1985-1987 and 1994-1996 were made using relative risks and 95% confidence intervals (CI). The overall fetal mortality rate due to congenital anomalies increased significantly, from 68.0 per 100,000 total births in 1985-1987 to 78.6 per 100,000 total births in 1994-1996, while the overall infant mortality rate due to congenital anomalies decreased significantly over the same period, from 2.47 to 1.79 per 1,000 live births. The fetal death rate due to congenital anomalies at 20-21 weeks of gestation increased approximately five-fold (relative risk [RR] = 4.83, 95% CI = 3.28-7.11) from 4.5 to 21.5 per 100,000 fetuses at risk, while the rate at 37-41 weeks decreased by 30% (RR = 0.70, 95% CI = 0.50-0.97). Fetal death rates among pregnancies at 20-25 weeks of gestation increased in all categories of congenital anomaly except anencephaly and respiratory system anomalies. Congenital anomaly-related fetal and infant deaths have increased at early gestation but declined at later gestation in Canada. These changes suggest an increase in prenatal diagnosis and selective termination of pregnancies with congenital anomalies in recent years., (Copyright 2001 Wiley-Liss, Inc.)

Objective: To examine whether the recent substantial increase in preterm birth among twins has been associated with changes in fetal and infant mortality., Design: Cohort study based on information in the linked live birth, stillbirth, and mortality databases of Statistics Canada., Setting: Ten of 12 provinces and territories in Canada., Participants: All twin live births and stillbirths between 1985 and 1996, along with information on deaths during infancy (1985-1997)., Main Outcome Measure: Fetal and infant mortality rates., Results: The rate of preterm birth among twin live births increased significantly by 17% (95% confidence interval: 14%-20%) from 42.5% between 1985 and 1987 to 49.6% between 1994 and 1996. Overall, stillbirth rates among twins declined from 22.4 per 1000 total births in 1985 to 1987 to 18.8 per 1000 total births in 1994 to 1996. Among twin fetuses >/=34 weeks' gestation, stillbirth rates decreased from 9.5 per 1000 in 1985 to 1987 to 5.4 per 1000 fetuses at risk in 1994 to 1996. Infant mortality rates among twin live births declined substantially in all categories of gestational age above 24 weeks except for live births at 32 to 33 and 34 to 36 weeks' gestation., Conclusions: The recent increase in preterm birth among twins was associated with a substantial reduction in stillbirth rates at and near term gestation. Infant mortality rates declined concurrently, although the absence of a significant decrease in infant mortality among twin live births at 32 to 33 and 34 to 36 weeks' gestational age needs additional scrutiny.

Preterm birth, a major determinant of infant mortality, has been increasing in recent years. The authors examined trends in preterm birth and its determinants by using the US birth and infant death files for 1989-1997. The impact of trends in preterm birth rates on neonatal and infant mortality was also evaluated. Among Whites, preterm births (<37 completed weeks of gestation) increased from 8.8% of livebirths in 1989 to 10.2% in 1997, a relative increase of 15.6%. On the other hand, preterm births among Blacks decreased by 7.6% (from 19.0% to 17.5%) during the same period. An increase in obstetric interventions contributed to increases in preterm births for both races but was outweighed by other unidentified favorable influences for Blacks. Neonatal mortality among preterm Whites dropped 34% during the 8 years of the study, while the decrease was only 24% among Blacks. This large disparity countered the changes in preterm birth rates so that the percentage decline in neonatal mortality was similar in the two racial groups (18-20%). In conclusion, the anticipated mortality benefit from a lower preterm birth rate for Blacks has been blunted by suboptimal improvement in mortality among the remaining preterm infants. The widening race gap in mortality among preterm infants merits attention.

Objective: To examine the causes and consequences of the recent increase in preterm birth among twins., Methods: We studied all twin births among residents of the province of Nova Scotia, Canada, between 1988 and 1997. Rates of preterm birth, preterm labor induction, preterm cesarean, small-for-gestational age (SGA), respiratory distress syndrome (RDS), stillbirth, perinatal mortality, and infant mortality were compared between past and more recent years. Changes in perinatal mortality were examined using logistic regression to adjust for the effects of other determinants., Results: The study included 2516 twin births (73 stillbirths and 2443 live births). The rate of preterm birth increased from 42.3% in 1988-1992 to 48.2% of twin live births in 1993-1997 (14% increase, P =.04). Twin live births born after preterm labor induction increased from 3.5% in 1988-1989 to 8.6% in 1996-1997 (P for trend =.007). Of live births between 34 and 36 weeks' gestation, the proportion born SGA decreased from 17.5% in 1988-1992 to 9.2% in 1993-1997 (P =.005). Over the same period, rates of prophylactic maternal steroid therapy increased substantially and rates of RDS declined. Perinatal mortality rates among pregnancies reaching 34 weeks decreased from 12.9 per 1000 total births in 1988-1992 to 4.2 per 1000 total births in 1993-1997 (P =.05)., Conclusion: Increases in preterm labor induction appear to be responsible for the recent increase in preterm birth among twins. These changes have been accompanied by decreases in perinatal morbidity and mortality among twin pregnancies that reach 34 weeks' gestation.

All births and infant deaths in 1985 87 and 1992 94 in Canada, except in Ontario and Newfoundland, were analyzed to assess the potential impact of the recent increased use of elective labour induction for post-term pregnancies. Probabilistic linkage was carried out of infant death records (Canadian Mortality Database) and respective birth registrations (Canadian Birth Database) for the periods 1985 87 and 1992 94. The combined fetal and infant mortality declined by 20 30% between 1985 87 and 1992 94 at each gestational week beginning at 37 weeks, with no increased reduction among post-term pregnancies. Asphyxia-related fetal and infant deaths, the most likely cause of death being preventable by labour induction for post-term pregnancies, did not decrease among post-term pregnancies. In contrary, a substantial decrease of asphyxia-related deaths was observed at 37 and 38 weeks over the same periods of time. Because fetal and infant deaths are rare events and because the number of pregnancies passing 42 weeks of gestation decreased dramatically during 1992 94, statistically unstable results may be inevitable in the comparison of mortality in this group of pregnancies.

We studied infant mortality rates in Canada within specific gestational age and birthweight categories after using probabilistic techniques to link information in Statistics Canada's live births data base (1985-94) with that in the death data base (1985-95). Gestational age- and birthweight-specific mortality rates in 1992-94 were contrasted with those in 1985-87 with changes expressed in terms of relative risks with 95% confidence intervals [CI]. Statistically significant reductions in infant mortality were observed beginning at 24-25 weeks of gestation and extended across the gestational age range to post-term births. Crude infant mortality rates, infant mortality rates among those > or = 500 g and among those > or = 1000 g decreased by 22%, 25% and 26%, respectively, from 1985-87 to 1992-94. The magnitude of the reductions in infant mortality rates ranged from 14% [95% CI 7, 21%] at 24-25 weeks of gestation to 40% [95% CI 31, 47%] at 28-31 weeks. Almost all reductions in gestational age- and birthweight-specific infant mortality between 1985-87 and 1992-94 were due to approximately equal reductions in neonatal and post-neonatal mortality. Live births > or = 42 weeks of gestation did not follow this rule; post-neonatal mortality rates among such live births decreased significantly by 51% [95% CI 26, 68%], although neonatal mortality rates showed no significant change. The mortality reductions observed across the gestational age and birthweight range are probably a consequence of specific clinical interventions complementing improvements in fetal growth. Temporal changes in the outcome of post-term pregnancies need to be carefully examined, especially in relation to recent changes in the obstetric management of such pregnancies.

Objective: To examine whether the magnitude of improvement in the health status of a population over time is dependent on the previous health status of that population., Design and Setting: A study of infant mortality rates in Canada's 12 provinces and territories between the periods 1961-1965 and 1991-1995, and of infant mortality rates in 133 countries between 1960 and 1995., Main Outcome Measures: Spearman's rank correlations, relative risks, and risk differences to measure the relationship between infant mortality in the 1960s and changes in infant mortality between the 1960s and 1990s., Results: In Canada, regional rankings based on infant mortality rates in 1961-1965 were strongly correlated (inversely) with rankings based on the percent change in infant mortality between 1961-1965 and 1991-1995 (correlation coefficient = -.85). In contrast, internationally, rankings based on infant mortality rates in 133 countries in 1960 were positively correlated with percent change between 1960 and 1995 (correlation coefficient =.56). Regional differences in infant mortality rates, measured using relative risks, declined in Canada (highest relative risk: 4.2, compared with Ontario in the 1960s; highest relative risk: 2.2, compared with Ontario in the 1990s) but increased globally (highest relative risk: 5.0, compared with industrialized countries in 1960; highest relative risk: 15.1, compared with industrialized countries in 1995)., Conclusions: Canadian regions with higher infant mortality rates in 1961-1965 achieved larger improvements compared with regions with initially lower infant mortality rates. The pattern observed within Canada is unlike the pattern observed internationally.

Background: We assessed the impact of recent advances in perinatal care on infant mortality due to congenital anomaly., Methods: Analysis of trends in congenital anomaly-attributed infant mortality, using the 1981-1995 Statistics Canada's birth and death records, with a total of 2,878,826 live births, 21,883 infant deaths, and 6, 908 infant deaths due to congenital anomalies., Results: Infant mortality due to major congenital anomaly decreased from 3.11 per 1, 000 live births in 1981 to 1.89 per 1,000 live births in 1995. Cause-specific infant mortality rates for anencephaly, spina bifida, other central nervous system anomalies, cardiovascular system anomalies, respiratory system anomalies, digestive system anomalies, certain musculoskeleton anomalies, urinary system anomalies, chromosomal anomalies, and multiple congenital anomalies were 0.20, 0.23, 0.27, 1.04, 0.24, 0.08, 0.22, 0.16, 0.22, and 0.13 per 1,000 live births, respectively, in 1981-1983, whereas corresponding rates were 0.07, 0.07, 0.18, 0.73, 0.25, 0.03, 0.12, 0.12, 0.26, and 0.06 per 1,000 live births, respectively, in 1993-1995., Conclusions: Recent Canadian data show that infant deaths caused by major congenital anomalies have decreased significantly, but reductions varied substantially according to specific forms of anomalies., (Copyright 2000 Wiley-Liss, Inc.)

Objective: To identify spatial patterns of changes in infant mortality rates and proportions of low-birth-weight live births observed in 1994., Setting: Canada., Subjects: Live births and infant deaths in Canada between 1987 and 1994. Data for Newfoundland were unavailable for 1987 through 1990., Outcome Measures: Annual infant mortality rates (crude and after excluding live newborns weighing less than 500 g); proportion of live births by low-birth-weight category (500-2499 g)., Results: Nova Scotia, New Brunswick, Quebec and Manitoba had lower crude and adjusted infant mortality rates in 1994 than in 1993. Newfoundland, Saskatchewan, Alberta and British Columbia had higher rates in 1994 than in 1993. The crude rate in Ontario was lower, and the adjusted rate higher, in 1994 than in 1993. A downward trend in the proportion of low-birth-weight live births was observed in Quebec (chi(2) for trend = 29.2, p < 0.01). Conversely, an upward trend was observed in Ontario (chi(2) for trend = 241.3, p < 0.01). However, the increase may have been due to data errors, especially in 1993 and 1994, involving truncation of ounces in 2 digits to 1 digit (e.g., 5 pounds 10 ounces became 5 pounds 1 ounce)., Conclusions: Although the marginal increases in infant mortality observed in several provinces could be the result of random variation, future trends should be closely monitored. The proportion of low-birth-weight live births in Canada (excluding Ontario) appears to be stable, with Quebec showing significant reductions. The errors in data for Ontario need to be corrected before trends can be estimated for that province and for Canada as a whole.

Objective: To ascertain whether the increase in the crude infant mortality rate in Canada in 1993 was due to a recent increase in the registration of newborns weighing less than 500 g as live births., Design: Ecological study, with Poisson regression analysis., Setting: Canada., Subjects: All live births and infant deaths in Canada between 1987 and 1993, as reported by Statistics Canada. Data from Newfoundland were excluded because they were incomplete for 4 years., Outcome Measures: Proportion of live births by low-birth-weight category; and annual crude and adjusted infant mortality rates., Results: Over the study period the proportion of newborns weighing less than 500 g registered as live births increased significantly (chi 2 for trend = 71.26, p < 0.01). This trend was an isolated phenomenon rather than a general increase in all low-birth-weight categories (chi 2 for trend in the proportion of newborns weighing 500 to 2400 g registered as live births = 1.14, p = 0.28). The crude infant mortality rate per 1000 live births decreased from 6.4 in 1991 to 6.1 in 1992 and then increased to 6.3 in 1993. Poisson regression analysis revealed that the apparent increase in the infant mortality rate was caused by the increased registration of infants weighing less than 500 g as live births. The adjusted infant mortality estimate for 1993 was lower than that for 1992., Conclusions: The increased infant mortality rate in Canada in 1993 appears to be due to increased registration of infants weighing less than 500 g as live births. Comparisons of infant mortality rates by place and time should be adjusted for the proportion of such live births, especially if the comparisons involve recent years.

A study was conducted examining the paradox that populations with a poor standard of health seem to achieve only meagre improvements over time, whereas those with a good standard of health seem to show continual, substantial improvement. The health states of 122 nations were measured by reference to their infant mortality in 1965 and the changes that occurred over the next 20 years. Countries with low infant mortality in 1965 (for example, Japan and East Germany) achieved substantial, further declines over the 20 years, whereas in countries such as Rwanda and Ethiopia infant mortality hardly declined at all or even increased (Ethiopia 165/1000 to 168/1000). In 48 countries for which data were available there was a close link between the change in health state of a people and the ratio of government expenditure on health and defence. As the ratio increased in favour of defence, so the improvement in health state of a people declined; the reverse was also true. At the primary care level disparity in uptake of care both among and within communities was associated with literacy and socioeconomic state, services inadvertently being aimed at those sections most likely to benefit. The forces that act to produce this setting of unequal care must be checked at both national and primary levels if we are to have "Health for All by the Year 2000."

Objective: To estimate trends in incidence and identify risk factors and maternal and neonatal consequences of eclampsia in Canada.Methods: We conducted a population-based cohort study of all women and their newborns (N=1,910,729) delivered in the hospital in Canada (excluding Quebec) from 2003 to 2009. The data were obtained from the Canadian Institute for Health Information. Logistic models were used to examine the association with potential determinants and consequences of eclampsia.Results: The incidence of eclampsia declined dramatically from 12.4 per 10,000 deliveries in 2003 to 5.9 in 2009. Among singleton deliveries, nulliparity (adjusted odds ratio [OR] 2.3; 95% confidence interval [CI] 2.0-2.6), anemia (adjusted OR 2.4; 95% CI 2.0-3.0), and existing heart disease (adjusted OR 4.8; 95% CI 2.9-7.3) increased the risk of eclampsia. The declining trend in eclampsia remained unchanged after accounting for changes in potential determinants and risk factors during the study period. Eclampsia was associated with increased risks of maternal death (adjusted OR 26.8; 95% CI 9.7-73.8), assisted ventilation (adjusted OR 102.3; 95% CI 78.2-133.8), respiratory distress syndrome (adjusted OR 36.2; 95% CI 15.3-85.3), acute renal failure (adjusted OR 20.9; 95% CI 11.4-38.3), obstetric embolism (adjusted OR 9.1; 95% CI 4.1-19.9), and other complications. Adverse neonatal outcomes associated with eclampsia included neonatal death (adjusted OR 2.9; 95% CI 1.6-5.5), respiratory distress syndrome (adjusted OR 5.1; 95% CI 4.1-6.3), and small-for-gestational age birth (adjusted OR 2.6; 95% CI 2.3-3.0).Conclusion: Despite declining incidence and improved care of women with eclampsia, the condition remains strongly associated with serious adverse consequences. [ABSTRACT FROM AUTHOR]

Examines the impact of prenatal diagnosis and pregnancy termination on overall infant mortality in Canada. Implications of selective pregnancy termination for reducing infant deaths; Relative risk percentage of pregnancy terminations; Decrease in congenital anomaly related infant mortality.

Investigates changes in fetal and infant mortality due to increases in preterm birth among twins in Canada. Decline of overall fetal mortality; Causes of fetal deaths; Impact of increased obstetric intervention.