Birth and postnatal outcomes among infants of immigrant parents of different admission categories and parents born in Canada: a population-based retrospective study.

BACKGROUND: Most studies of disparities in birth and postnatal outcomes by parental birthplace combine all immigrants into a single group. We sought to evaluate heterogeneity among immigrants in Canada by comparing birth and postnatal outcomes across different immigration categories. METHODS: We conducted a population-based retrospective study using Statistics Canada data on live births and stillbirths (1993-2017) and infant deaths (1993-2018), linked to parental immigration data (1960-2017). We classified birthing parents as born in Canada, economic-class immigrants, family-class immigrants, or refugees, and evaluated differences in preterm births, small-for-gestational-age (SGA) and large-for-gestational-age (LGA) births, stillbirths, and infant deaths among singleton births by group. RESULTS: Among 7 980 650 births, 1 715 050 (21.5%) were to immigrants, including 632 760 (36.9%) in the economic class, 853 540 (49.8%) in the family class, and 228 740 (13.4%) refugees. Compared with infants of Canadian-born birthing parents, infants of each of the 3 immigrant groups had higher risk of preterm birth, SGA birth, and stillbirth, but lower risk of LGA birth and neonatal death. Compared with infants of economic-class immigrants, infants of refugees had higher risk of early preterm birth (0.9% v. 0.8%, adjusted risk ratio [RR] 1.08, 95% confidence interval [CI] 1.01-1.15) and LGA birth (9.2% v. 7.5%, adjusted RR 1.12, 95% CI 1.10-1.15), but lower risk of SGA birth (10.2% v. 11.0%, adjusted RR 0.92, 95% CI 0.90-0.94), while infants of family-class immigrants had higher risk of SGA birth (12.2% v. 11.0%, adjusted RR 1.01, 95% CI 1.00-1.02). Risk of stillbirth, neonatal death, and overall infant death did not differ significantly among immigrant groups. INTERPRETATION: Heterogeneity exists in outcomes of infants born to immigrants to Canada across immigration categories. These results highlight the importance of disaggregating immigrant populations in studies of health disparities.

In utero Exposure to Maternal Diabetes and the Risk of Cerebral Palsy: A Population-based Cohort Study.

BACKGROUND: Evidence on the effects of in utero exposure to maternal diabetes on cerebral palsy (CP) in offspring is limited. We aimed to examine the effects of pregestational (PGDM) and gestational diabetes (GDM) separately on CP risk and the mediating role of increased fetal size. METHODS: In a population-based study, we included all live births in Ontario, Canada, between 2002 and 2017 followed up through 2018 (n = 2,110,177). Using administrative health data, we estimated crude and adjusted associations between PGDM or GDM and CP using Cox proportional hazards models to account for unequal follow-up in children. For the mediation analysis, we used marginal structural models to estimate the controlled direct effect of PGDM (and GDM) on the risk of CP not mediated by large-for-gestational age (LGA). RESULTS: During the study period, 5,317 children were diagnosed with CP (187 exposed to PGDM and 171 exposed to GDM). Children of mothers with PGDM showed an increased risk (hazard ratio [HR]: 1.84 [95% confidence interval (CI): 1.59, 2.14]) after adjusting for maternal sociodemographic and clinical factors. We found no associations between GDM and CP (adjusted HR: 0.91 [0.77, 1.06]). Our mediation analysis estimated that LGA explained 14% of the PDGM-CP association. CONCLUSIONS: In this population-based birth cohort study, maternal pregestational diabetes was associated with increased risk of CP, and the increased risk was not substantially mediated by the increased fetal size.

Prevalence and temporal trends of cerebral palsy in children born from 2002 to 2017 in Ontario, Canada: Population-based cohort study.

AIM: To examine the prevalence and temporal trends of cerebral palsy (CP) overall and by population characteristics. METHOD: We identified 2 110 177 live births born in the province of Ontario, Canada, between 2002 and 2017 using administrative health data and estimated CP prevalence in children aged 0 to 16 years overall and by specific population characteristics. We also examined temporal trends in CP rates - overall and by characteristics - in young children (0-4 years) by their year of birth between 2002 and 2013 (n=1 587 087 live births) to allow for an equal follow-up time (4 years and 364 days) for all children. RESULTS: Overall CP prevalence among children aged 0 to 16 years was 2.52 (95% confidence interval 2.45-2.59) per 1000 live births. CP rates in ages 0 to 4 years peaked at 2.86 in 2007 births, but steadily declined afterwards to 1.94 per 1000 live births in 2013. CP rates were higher in children born preterm, small for gestational age, males, multiples, children with congenital malformations, and in children of young (<20 years), old (≥40 years), primiparous, or grand multiparous (≥4) mothers; differences by these characteristics decreased over time. We observed socioeconomic disparities in CP rates that persisted over time. INTERPRETATION: Despite the decreasing trend of CP rates overall, CP rates varied by the child and maternal characteristics over time. WHAT THIS PAPER ADDS: Overall cerebral palsy (CP) prevalence was 2.5 per 1000 live births among children born from 2002 to 2017. CP prevalence peaked in children born in 2007 then steadily decreased between 2007 and 2013. Changes in CP rates varied over time by child and maternal characteristics. Socioeconomic inequalities in CP persisted and remained stable over the study period.

Prenatal Exposure to Insecticides and Weight Trajectories Among South African Children in the VHEMBE Birth Cohort.

BACKGROUND: Dichlorodiphenyltrichloroethane (DDT) or pyrethroid insecticides are sprayed inside dwellings for malaria vector control, resulting in high exposure to millions of people, including pregnant women. These chemicals disrupt endocrine function and may affect child growth. To our knowledge, few studies have investigated the potential impact of prenatal exposure to DDT or pyrethroids on growth trajectories. METHODS: We investigated associations between gestational insecticide exposure and child growth trajectories in the Venda Health Examination of Mothers, Babies and their Environment, a birth cohort of 751 children born between 2012 and 2013 in South Africa. Based on child weight measured at follow-up and abstracted from medical records, we modeled weight trajectories from birth to 5 years using SuperImposition, Translation and Rotation, which estimated two child-specific parameters: size (average weight) and tempo (age at peak weight velocity). We estimated associations between peripartum maternal concentrations of serum DDT, dichlorodiphenyldichloroethylene, or urinary pyrethroid metabolites and SuperImposition, Translation and Rotation parameters using marginal structural models. RESULTS: We observed that a 10-fold increase in maternal concentrations of the pyrethroid metabolite trans-3-(2,2,-dicholorvinyl)-2,2-dimethyl-cyclopropane carboxylic acid was associated with a 21g (95% confidence interval = -40, -1.6) smaller size among boys but found no association among girls (Pinteraction = 0.07). Estimates suggested that pyrethroids may be associated with earlier tempo but were imprecise. We observed no association with serum DDT or dichlorodiphenyldichloroethylene. CONCLUSIONS: Inverse associations between pyrethroids and weight trajectory parameters among boys are consistent with hypothesized disruption of androgen pathways and with our previous research in this population, and support the endocrine-disrupting potential of pyrethroids in humans.

Differences in birthweight by maternal and paternal nativity status in Canada.

BACKGROUND: Parental nativity, as well as duration of residence of foreign-born parents in the host country, has been shown to be associated with size at birth. However, most studies have focused on maternal nativity status only and have not accounted for important characteristics of both parents. OBJECTIVE: To explore whether maternal and paternal nativity and length of residence (LOR) are independently associated with birthweight for gestational age in a representative sample of infants in Canada. METHODS: We compared mean differences in sex- and gestational age-standardised birthweight z-score by nativity status of both parents in a nationally representative sample of 130,532 singleton infants born between May 2004 and May 2006 to mothers residing in Canada. We categorised parental nativity status into four groups (both parents Canada-born, mother only foreign-born, father only foreign-born and both parents foreign-born) and parents' LOR into three (both ≤10 years, only one parent ≤10 years and both >10 years). We estimated mean differences in birthweight z-score and their 95% confidence intervals in linear regression models adjusted for parity, parents' ages, education, ethnicity and marital status of the mother. RESULTS: Compared with babies of Canada-born couples, those of two foreign-born parents had on average smaller birthweight z-score, -0.23 (95% CI -0.28, -0.25). However, after adjustment, the mean difference in z-score was -0.02 (95% CI -0.05, 0.00). Infants born to parents who had both resided in Canada for ≤10 years had a unadjusted mean difference in z-score of -0.27 (95% CI -0.29, -0.26), compared infants whose parents were both Canada-born, but the difference became negligible (-0.02, 95% CI -0.04, 0.01) after adjustment. CONCLUSION: The birthweight differences by parental nativity or length of residence observed in our study population could be attributed to differences in the distribution of other parental characteristics that affect birthweight.

Effects of mobile networks and Covid-19 on mobile shopping sales in South Korea.

Covid-19 has driven us abruptly to a new world of contactless society. It also compelled us to use online shopping, especially mobile shopping in South Korea, where the dominant mode of wireless communication was already 4G services when Covid-19 broke out. This paper examines the different roles of mobile networks and the Covid-19 pandemic in transforming mobile shopping submarkets in South Korea by estimating the long-term and short-term effects of these two factors on mobile shopping sales. We used a cointegration and an error correction model to estimate long-term and short-term effects separately. This paper finds that Covid-19 was a major short-term factor affecting sales in mobile shopping submarkets, while mobile network subscribers were a key long-term driving factor of mobile shopping sales growth.

Effect of preschool childcare on school-aged children's adiposity in Quebec, Canada.

BACKGROUND: Regulated public childcare must follow nutrition and physical activity guidelines, but the impact of public childcare on childhood adiposity is unclear. OBJECTIVES: To estimate the effects of universal preschool childcare on children's BMI in elementary school in Quebec, Canada, and whether the effects differed in children from more or less advantaged families. METHODS: For 1657 children enrolled in the Quebec Longitudinal Study of Child Development (1998-2010), BMI z-scores (BMIz) from 6 to 13 years were regressed on the childcare used from 2 to 5 years, adjusted for pre-childcare variables. Average treatment effects were estimated using the Bayesian multilevel linear regression and g-computation for four childcare profiles: 1) parental care or full-time care (35 hours/week) in a 2) centre-based, 3) regulated home-based or 4) unregulated home-based arrangement. RESULTS: Had all participants attended centre-based care, mean BMIz in kindergarten would have been 0.38 (95% credible interval [CrI] 0.23, 0.52), which was 0.40 (95% CrI 0.14, 0.65) SD higher than regulated home-based, 0.20 (95% CrI -0.04, 0.43) SD higher than unregulated home-based and 0.36 (95% CrI 0.11, 0.60) SD higher than parental care. By 12 years, mean BMIz had increased for all childcare profiles, but differences between childcare profiles had diminished. CONCLUSIONS: Although centre-based childcare was associated with an earlier rise in BMI, compared with informal care, it had no large, enduring effect, overall, or for less advantaged children, in particular.

Growth During Infancy and Early Childhood and Its Association With Metabolic Risk Biomarkers at 11.5 Years of Age.

The evidence that fetal life and early infancy are "critical" or "sensitive" ages for later development of cardiometabolic disease is based on flawed methods for comparing different age periods. Moreover, most previous studies have limited their focus to weight gain, rather than growth in length/height or body mass index (weight (kg)/height (m)2). We undertook a secondary analysis of data from the Promotion of Breastfeeding Intervention Trial (1996-2010), a birth cohort study nested within a large cluster-randomized trial in the Republic of Belarus, that had repeated measurements of weight and length/height taken from birth to 11.5 years of age. We used mixed-effects linear models to analyze associations of changes in standardized weight, length/height, and body mass index during 5 age periods (conception to birth, birth to age 3 months, ages 3-12 months, ages 12 months-6.5 years, and ages 6.5-11.5 years) with fasting glucose, insulin, insulin resistance, ß-cell function, and adiponectin at age 11.5 years. We observed strong associations between the metabolic markers and all 3 growth measures, with the largest magnitudes being observed during the latest age period (ages 6.5-11.5 years) and negligible associations during gestation and the first year of life. Later age periods appear more "sensitive" than earlier periods to the adverse metabolic association with rapid growth in childhood.

Perinatal health among foreign versus native-born mothers in Canada: variations across outcomes and cohorts.

BACKGROUND: To examine perinatal health differences between foreign-born and native-born mothers in Canada across multiple outcomes and two cohorts 10 years apart. METHODS: Using 94 896 and 131 271 births in the 1996 and 2006 Canadian Census-Birth Cohort, respectively, we estimated risk ratios and risk differences of preterm birth (PTB), small-for-gestational age (SGA), large-for-gestational age (LGA), stillbirth and infant mortality between foreign-born and Canadian-born mothers. RESULTS: In the 1996 cohort, we observed no important differences in adverse outcomes between foreign-born and native-born mothers. In the 2006 cohort, however, foreign-born mothers had lower risks of PTB, LGA, stillbirth, and infant mortality and a higher risk of SGA on both the relative and absolute scales. Lowered risk of PTB among foreign-born mothers in the 2006 cohort was also observed within Caucasian, East Asian, Southeast Asian and South Asian mothers. Favourable outcomes associated with foreign-born status in the 2006 cohort were negatively graded by duration of residence in Canada among immigrant mothers. CONCLUSIONS: Differences in perinatal health by maternal foreign-born status varied across cohorts and a more pronounced 'healthy migrant' effect was observed among more recent migrants. The native-born mothers' perinatal health over time and a more restrictive/selective immigration policy in recent years would explain our results.

Associations of atopic dermatitis and asthma with child behaviour: Results from the PROBIT cohort.

BACKGROUND: Conflicting findings from studies evaluating associations of allergic disease with child behaviour require longitudinal studies to resolve. OBJECTIVE: To estimate the magnitude of associations of atopic dermatitis (AD) in infancy, and symptoms of asthma and AD at 6.5 years, with child behaviour at 6.5 years. METHODS: Secondary cohort analysis of the Promotion of Breastfeeding Intervention Trial (PROBIT). PROBIT enrolled 17 046 infants at birth and followed them up at 6.5 years (n = 13 889). Study paediatricians collected data on infantile AD at repeated follow-up examinations during the first year of life. At 6.5 years, paediatricians performed skin prick tests and parents reported asthma and AD symptoms during the prior year. In addition, parents and teachers completed the Strength and Difficulties Questionnaire, which includes scales on hyperactivity/inattention, emotional problems, conduct problems, peer problems and prosocial behaviours. RESULTS: Physician-diagnosed AD in the first year of life was not associated with increased risk for behavioural problems at 6.5 years. Emotional problems at 6.5 years were more common among children with AD symptoms (OR: 2.24, 95% CI: 1.62-3.12) and asthma symptoms (OR: 1.45; 95% CI: 1.07-1.96) during the past year at 6.5 years and ORs for children with symptoms of more severe AD and asthma were also higher. AD in the past year was also associated with probable hyperactivity/inattention disorder at 6.5 years (OR: 2.05; 95% CI: 1.09-3.84). Other subscales of the SDQ were not related to asthma or AD symptoms during the past year. CONCLUSIONS AND CLINICAL RELEVANCE: Children with AD symptoms were at higher risk for concomitant hyperactivity/inattention and emotional disorder, and children with asthma symptoms were at higher risk of having concomitant emotional problems. However, AD during infancy did not predict childhood behaviours.

Assessment of eating attitudes and dieting behaviors in healthy children: Confirmatory factor analysis of the Children's Eating Attitudes Test.

OBJECTIVE: The Children's Eating Attitudes Test (ChEAT) is a self-report questionnaire that is conventionally summarized with a single score to identify "problematic" eating attitudes, masking informative variability in different eating attitude domains. This study evaluated the empirical support for single- versus multifactor models of the ChEAT. For validation, we compared how well the single- versus multifactor-based scores predicted body mass index (BMI). METHOD: Using data from 13,674 participants of the 11.5 year-follow-up of the Promotion of Breastfeeding Intervention Trial (PROBIT) in the Republic of Belarus, we conducted confirmatory factor analysis to evaluate the performance of 3- and 5-factor models, which were based on past studies, to a single-factor model representing the conventional summary of the ChEAT. We used cross-validated linear regression models and the reduction in mean squared error (MSE) to compare the prediction of BMI at 11.5 and 16 years by the conventional and confirmed factor-based ChEAT scores. RESULTS: The 5-factor model, based on 14 of the original 26 ChEAT items, had good fit to the data whereas the 3- and single-factor models did not. The MSE for concurrent (11.5 years) BMI regressed on the 5-factor ChEAT summary was 35% lower than that of the single-score models, which reduced the MSE from the null model by only 1%-5%. The MSE for BMI at 16 years was 20% lower. DISCUSSION: We found that a parsimonious 5-factor model of the ChEAT explained the data collected from healthy Belarusian children better than the conventional summary score and thus provides a more discriminating measure of eating attitudes.

Breastfeeding during infancy and neurocognitive function in adolescence: 16-year follow-up of the PROBIT cluster-randomized trial.

BACKGROUND: Evidence on the long-term effect of breastfeeding on neurocognitive development is based almost exclusively on observational studies. In the 16-year follow-up study of a large, cluster-randomized trial of a breastfeeding promotion intervention, we evaluated the long-term persistence of the neurocognitive benefits of the breastfeeding promotion intervention previously observed at early school age. METHODS AND FINDINGS: A total of 13,557 participants (79.5% of the 17,046 randomized) of the Promotion of Breastfeeding Intervention Trial (PROBIT) were followed up at age 16 from September 2012 to July 2015. At the follow-up, neurocognitive function was assessed in 7 verbal and nonverbal cognitive domains using a computerized, self-administered test battery among 13,427 participants. Using an intention-to-treat (ITT) analysis as our prespecified primary analysis, we estimated cluster- and baseline characteristic-adjusted mean differences between the intervention (prolonged and exclusive breastfeeding promotion modelled on the Baby-Friendly Hospital Initiative) and control (usual care) groups in 7 cognitive domains and a global cognitive score. In our prespecified secondary analysis, we estimated mean differences by instrumental variable (IV) analysis to account for noncompliance with the randomly assigned intervention and estimate causal effects of breastfeeding. The 16-year follow-up rates were similar in the intervention (79.7%) and control groups (79.3%), and baseline characteristics were comparable between the two. In the cluster-adjusted ITT analyses, children in the intervention group did not show statistically significant differences in the scores from children in the control group. Prespecified additional adjustment for baseline characteristics improved statistical precision and resulted in slightly higher scores among children in the intervention for verbal function (1.4 [95% CI 0.3-2.5]) and memory (1.2 [95% CI 0.01-2.4]). IV analysis showed that children who were exclusively breastfed for ≥3 (versus <3) months had a 3.5-point (95% CI 0.9-6.1) higher verbal function, but no differences were observed in other domains. While our computerized, self-administered cognitive testing reduced the cluster-level variability in the scores, it may have increased individual-level measurement errors in adolescents. CONCLUSIONS: We observed no benefit of a breastfeeding promotion intervention on overall neurocognitive function. The only beneficial effect was on verbal function at age 16. The higher verbal ability is consistent with results observed at early school age; however, the effect size was substantially smaller in adolescence. PROBIT TRIAL REGISTRATION: ClinicalTrials.gov NCT01561612.

Does Fetal Growth Restriction Cause Later Obesity? Pitfalls in Analyzing Causal Mediators as Confounders.

Recent studies finding that small-for-gestational-age (SGA) birth is associated with increased adiposity in childhood and adulthood have been based on analyses "adjusting" for height, weight, or body mass index (BMI; weight (kg)/height (m)2) measured concurrently with the adiposity measurement. To assess the potential for bias due to overadjustment for a causal mediator, we compared 2 approaches to analyzing the association between SGA birth and adiposity outcomes (skinfold thicknesses and bioelectrical impedance measurement of body fat) at age 11.5 years using the same data set in a cohort of Belarusian children followed from birth in 1996-1997 to age 11.5 years in 2008-2010. We 1) studied the association of SGA birth with adiposity, adjusting for baseline covariates only, and 2) made additional regression adjustment for concurrent height, weight, or BMI. The first approach yielded negative associations between SGA birth and all adiposity outcomes. Additional adjustment for concurrent weight or BMI reversed (i.e., to positive) the SGA-adiposity association. To explore the latter anthropometric measures as causal mediators, we also used marginal structural models to estimate the controlled direct effect of SGA birth. That effect was similar to the effect seen with the first approach when modeled on height, was null when modeled on BMI, but was confounded by differences in lean mass versus fat mass when modeled on weight.

Socioeconomic disparities in small-for-gestational-age birth and preterm birth.

BACKGROUND: Maternal socioeconomic disadvantage has been associated with increased risk of small-for-gestational-age birth and preterm birth. Few studies, however, have considered maternal education and income simultaneously to better understand the mechanisms underlying perinatal health disparities. This analysis examines both maternal education and income and their association with the risk of small-for-gestational-age birth and preterm birth. DATA AND METHODS: The study is based on 127,694 singleton live births from the 2006 Canadian Birth-Census Cohort, a national cohort of births registered from May 2004 to May 2006 that were linked to the 2006 long-form Census. Unadjusted rates of small-for-gestational-age birth (sex-specific birth weight below the 10th percentile for gestational age) and preterm birth (before 37 completed weeks of gestation) were estimated across selected maternal characteristics. Logistic regression was used to estimate crude and covariate-adjusted risk ratios of both outcomes according to maternal education and income adequacy quintiles. RESULTS: Small-for-gestational-age birth was associated with both maternal education and income adequacy, while preterm birth was associated with maternal education only. These findings persisted after taking factors including maternal age, ethnicity, and marital status into account. The results suggest that the mechanism by which maternal education is associated with these outcomes is likely not through income, nor does income replace education as a potentially meaningful measure of socioeconomic position. INTERPRETATION: The mechanisms underlying associations between socioeconomic position and perinatal health disparities are complex. The results of this study indicate that more than one socioeconomic factor may play a role.

Birth outcomes among First Nations, Inuit and Métis populations.

BACKGROUND: First Nations, Inuit, and Métis are at higher risk of adverse birth outcomes than are non-Indigenous people. However, relatively little perinatal information is available at the national level for Indigenous people overall or for specific identity groups. DATA AND METHODS: This analysis describes and compares rates of preterm birth, small-for-gestational-age birth, large-for-gestational-age birth, stillbirth, and infant mortality (neonatal, postneonatal, and cause-specific) in a nationally representative sample of First Nations, Inuit, Métis, and non-Indigenous births. The study cohort consisted of 17,547 births to Indigenous mothers and 112,112 births to non-Indigenous mothers from 2004 through 2006. The cohort was created by linking the Canadian Live Birth, Infant Death and Stillbirth Database to the long form of the 2006 Census, which contains a self-reported Indigenous identifier. RESULTS: With the exception of small-for-gestational-age birth, adverse birth outcomes occurred more frequently among First Nations, Inuit, and Métis women than among non-Indigenous women. Inuit had the highest preterm birth rate (11.4 per 100 births; 95% CI: 9.7 to 13.1) among the three Indigenous groups. The large-for-gestational-age rate was highest for First Nations births (20.9 per 100 births; 95% CI: 19.9 to 21.8). Infant mortality rates were more than twice as high for each Indigenous group compared with the non-Indigenous population, and rates of sudden infant death syndrome were more than seven times higher among First Nations and Inuit. DISCUSSION: The results confirm disparities in birth outcomes between Indigenous and non-Indigenous populations, and demonstrate differences among First Nations, Métis and Inuit.

Comparison of black-white disparities in preterm birth between Canada and the United States.

BACKGROUND: A higher risk of preterm birth among black women than among white women is well established in the United States. We compared differences in preterm birth between non-Hispanic black and white women in Canada and the US, hypothesizing that disparities would be less extreme in Canada given the different historical experiences of black populations and Canada's universal health care system. METHODS: Using data on singleton live births in Canada and the US for 2004-2006, we estimated crude and adjusted risk ratios and risk differences in preterm birth (< 37 wk) and very preterm birth (< 32 wk) among non-Hispanic black versus non-Hispanic white women in each country. Adjusted models for the US were standardized to the covariate distribution of the Canadian cohort. RESULTS: In Canada, 8.9% and 5.9% of infants born to black and white mothers, respectively, were preterm; the corresponding figures in the US were 12.7% and 8.0%. Crude risk ratios for preterm birth among black women relative to white women were 1.49 (95% confidence interval [CI] 1.32 to 1.66) in Canada and 1.57 (95% CI 1.56 to 1.58) in the US (p value for heterogeneity [pH] = 0.3). The crude risk differences for preterm birth were 2.94 (95% CI 1.91 to 3.96) in Canada and 4.63 (95% CI 4.56 to 4.70) in the US (pH = 0.003). Adjusted risk ratios for preterm birth (pH = 0.1) were slightly higher in Canada than in the US, whereas adjusted risk differences were similar in both countries. Similar patterns were observed for racial disparities in very preterm birth. INTERPRETATION: Relative disparities in preterm birth and very preterm birth between non-Hispanic black and white women were similar in magnitude in Canada and the US. Absolute disparities were smaller in Canada, which reflects a lower overall risk of preterm birth in Canada than in the US in both black and white populations.

Missing paternal data and adverse birth outcomes in Canada.

BACKGROUND: Research on predictors of birth outcomes tends to focus on maternal characteristics. Less is known about the role of paternal factors. Missing paternal data on administrative records may be a marker for risk of adverse birth outcomes. DATA AND METHODS: Analyses were performed on a cohort of births that occurred from May 16, 2004 through May 15, 2006, which was created by linking birth and death registration data with the 2006 Canadian census. Log-binomial and binomial regression were used to estimate relative risks and risk differences for preterm birth, small-for-gestational-age birth, stillbirth and infant mortality associated with the absence of paternal information. Analyses controlled for maternal age, education, household income, parity, marital status, ethnicity and birthplace. RESULTS: The analyses pertained to 135,285 singleton births. Paternal data were missing from the birth registration for 7,461 births (4.6%) and from the census data for 17,713 births (11.4%). The adjusted relative risks associated with missing paternal data on the birth registration were 1.12 (95% CI: 0.99, 1.26) for preterm birth; 1.15 (1.05, 1.26) for small-for-gestational-age birth; 1.86 (1.27, 2.73) for stillbirth; and 1.53 (1.00, 2.34) for infant mortality. Estimates were robust to varying definitions of missing paternal information, based on the birth registration, census data, or both. INTERPRETATION: This study suggests that missing paternal data is a marker for increased risk of adverse birth outcomes, over and above maternal characteristics.

The 2006 Canadian Birth-Census Cohort.

BACKGROUND: Evidence on socioeconomic and ethnocultural disparities in perinatal health in Canada tends to be limited to analyses by neighbourhood or for selected provinces. In 2010, the Canadian Institutes of Health Research awarded funding for a project on perinatal outcomes. This article describes the resulting 2006 Canadian Birth-Census Cohort Database. DATA AND METHODS: From the Canadian Live Birth, Infant Death and Stillbirth Database, 687,340 records of children born in Canada from May 16, 2004 through May 15, 2006 to mothers whose usual place of residence was Canada were selected as in-scope births. Deterministic rules were applied to link each person on the birth record-child, mother, father-to 2006 Census data.The cohort was restricted to records linked to a long-form questionnaire, and a cohort weight was developed. Cohort rates (unweighted and weighted) for five birth outcomes-preterm birth, small-for-gestational age, large-for-gestational age, stillbirth, and infant mortality-were compared with rates for all in-scope births across birth characteristics. Cohort rates for these birth outcomes were examined across selected census characteristics. RESULTS: Linkage rates were 91% for births surviving to age 1, 76% for stillbirths, and 80% for infant deaths matched to a birth registration. The cohort estimates were similar to those for all in-scope births, particularly after the cohort weight was applied. The cohort data produced plausible estimates of selected birth outcomes across maternal ethnocultural categories and levels of education. INTERPRETATION: The 2006 Canadian Birth-Census Cohort data can help inform perinatal surveillance and research in Canada.

Neighborhood deprivation and maternal psychological distress during pregnancy: a multilevel analysis.

Maternal psychosocial distress is conceptualized as an important factor underlying the association between neighborhood deprivation and pregnancy outcomes. However, empirical studies to examine effects of neighborhood deprivation on psychosocial distress during pregnancy are scant. Based on a large multicenter cohort of pregnant women in Montreal, we examined (1) the extent to which psychosocial distress is clustered at the neighborhood-level, (2) the extent to which the clustering is explained by neighborhood material or social deprivation, and (3) whether associations between neighborhood deprivation and psychosocial distress persist after accounting for neighborhood composition (individual-level characteristics) using multilevel analyses. For 5,218 women residing in 740 neighborhoods, a prenatal interview at 24-26 gestational weeks measured both general and pregnancy-related psychological distress using well-validated scales: perceived stress, social support, depressive symptoms, optimism, commitment to the pregnancy, pregnancy-related anxiety, and maternal locus-of-control. Neighborhood deprivation indices were linked to study participants by their residential postal code. Neighborhood-level clustering (intraclass correlation) ranged from 1 to 2 % for perceived stress (lowest), optimism, pregnancy-related anxiety, and commitment to pregnancy to 4-6 % for perceived social support, depressive symptoms, and maternal locus of control (highest). Neighborhood material deprivation explained far more of the clustering (23-75 %) than did social deprivation (no more than 4 %). Although both material and social deprivation were associated with psychological distress in unadjusted analyses, the associations disappeared after accounting for individual-level socioeconomic characteristics. Our results highlight the importance of accounting for individual-level socioeconomic characteristics in studies of potential neighborhood effects on maternal mental health.

Exposure to parental smoking and child growth and development: a cohort study.

BACKGROUND: Studies on adverse childhood health and development outcomes associated with parental smoking have shown inconsistent results. Using a cohort of Belarusian children, we examined differences in cognition, behaviors, growth, adiposity, and blood pressure at 6.5 years according to prenatal and postnatal exposure to parental smoking. METHODS: Using cluster-adjusted multivariable regression, effects of exposure to prenatal smoking were examined by comparing (1) children whose mothers smoked during pregnancy with those of mothers who smoked neither during nor after pregnancy and (2) children whose mothers smoked during and after pregnancy with those whose mothers smoked after pregnancy only; effects of postnatal smoking were examined by comparing (1) children whose mothers smoked after pregnancy only with those of mothers who smoked neither during nor after pregnancy and (2) children whose fathers smoked with those whose fathers did not smoke among children of non-smoking mothers after adjusting for a wide range of socioeconomic and family characteristics. RESULTS: After adjusting for confounders, children exposed vs unexposed to prenatal maternal smoking had no differences in mean IQ, teacher-rated behavioral problems, adiposity, or blood pressure. Children exposed to maternal postnatal smoking had slightly increased behavioral problems [0.9, 95% CI: 0.6, 1.2 for total difficulties], higher body mass index [0.2, 95% CI: 0.1, 0.3], greater total skinfold thickness [0.4, 95% CI: 0.04, 0.71], and higher odds of overweight or obesity [1.4, 95% CI; 1.1, 1.7]. Similar magnitudes of association were observed with postnatal paternal smoking. CONCLUSIONS: No adverse cognitive, behavioral and developmental outcomes were associated with exposure to maternal prenatal smoking. Observed associations with postnatal smoking of both parents may reflect residual confounding by genetic and family environmental factors.