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Background While there is increasing interest in identifying pregnancies at risk for adverse outcome, existing prediction models have not adequately assessed population-based risks, and have been based on conventional regression methods. The objective of the current study was to identify predictors of fetal growth abnormalities using logistic regression and machine learning methods, and compare diagnostic properties in a population-based sample of infants. Methods Data for 30,705 singleton infants born between 2009 and 2014 to mothers resident in Nova Scotia, Canada was obtained from the Nova Scotia Atlee Perinatal Database. Primary outcomes were small (SGA) and large for gestational age (LGA). Maternal characteristics pre-pregnancy and at 26 weeks were studied as predictors. Logistic regression and select machine learning methods were used to build the models, stratified by parity. Area under the curve was used to compare the models; relative importance of predictors was compared qualitatively. Results 7.9% and 13.5% of infants were SGA and LGA, respectively; 48.6% of births were to primiparous women and 51.4% were to multiparous women. Prediction of SGA and LGA was poor to fair (area under the curve 60–75%) and improved with increasing parity and pregnancy information. Smoking, previous low birthweight infant, and gestational weight gain were important predictors for SGA; pre-pregnancy body mass index, gestational weight gain, and previous macrosomic infant were the strongest predictors for LGA. Conclusions The machine learning methods used in this study did not offer any advantage over logistic regression in the prediction of fetal growth abnormalities. Prediction accuracy for SGA and LGA based on maternal information is poor for primiparous women and fair for multiparous women.

In this randomized trial comparing delivery strategies in women with twin gestation, planned cesarean section did not significantly increase or decrease the risk of fetal or neonatal death or serious neonatal morbidity, as compared with planned vaginal delivery. Because of assisted reproductive technologies, twin pregnancy occurs more frequently now than in the past, and it complicates 2 to 3% of all births. 1 , 2 Twins are at higher risk for an adverse perinatal outcome than singletons. 3 , 4 Planned cesarean section, as compared with planned vaginal delivery, may reduce this risk. 5 Although a small, randomized, controlled trial did not show better perinatal outcomes with planned cesarean section than with planned vaginal delivery, 6 several cohort studies have shown a reduced risk of adverse perinatal outcomes for both twins, or for the second twin, when twins at or near term were delivered . . .

We conducted a linked database cohort study of infants born between 1990 and 2002 in Nova Scotia, Canada. Diagnoses of autism were identified from administrative databases with relevant diagnostic information to 2005. A factor representing genetic susceptibility was defined as having an affected sibling or a mother with a history of a psychiatric or neurologic condition. Among 129,733 children, there were 924 children with an autism diagnosis. The results suggest that among those with low genetic susceptibility, some maternal and obstetric factors may have an independent role in autism etiology whereas among genetically susceptible children, these factors appear to play a lesser role. The role of pre-pregnancy obesity and excessive weight gain during pregnancy on autism risk require further investigation.

The health care system in Canada provides essential health services to all women irrespective of socioeconomic status. Our objective was to determine whether perinatal and infant outcomes varied by family income and other socioeconomic factors in this setting. We included all 92,914 women who delivered in Nova Scotia between 1988 and 1995 following a singleton pregnancy. Family income was obtained for 76,440 of these women through a confidential link to income tax records and was divided into 5 groups. Outcomes studied included pregnancy complications, preterm birth, small-for-gestational-age live birth, perinatal death, serious neonatal morbidity, postneonatal death and infant death. Logistic regression models were used to adjust for potential confounders. Compared with women in the highest family income group, those in the lowest income group had significantly higher rates of gestational diabetes (crude rate ratio [RR] 1.44, 95% confidence interval [CI] 1.21-1.73), preterm birth (crude RR 1.20, 95% CI 1.06-1.35), small-for-gestational-age live birth (crude RR 1.81, 95% CI 1.66-1.97) and postneonatal death (crude RR 5.54, 95% CI 2.21-13.9). The opposite was true for rates of perinatal death (crude RR 0.74, 95% CI 0.56-0.96), and there was no significant difference between the 2 groups in the composite of perinatal death or serious neonatal morbidity (crude RR 1.01, 95% CI 0.82-1.24). Adjustment for behavioural and lifestyle factors accentuated or attenuated socioeconomic differences. Lower family income is associated with increased rates of gestational diabetes, small-for-gestational-age live birth and postneonatal death despite health care services being widely available at no out-of-pocket expense.

Background The literature shows a variable and inconsistent relationship between socioeconomic position and preterm birth. We examined risk factors for spontaneous and iatrogenic preterm birth, with a focus on socioeconomic position and clinical risk factors, in order to explain the observed inconsistency. Methods We carried out a retrospective population-based cohort study of all singleton deliveries in Nova Scotia from 1988 to 2003. Data were obtained from the Nova Scotia Atlee Perinatal Database and the federal income tax T1 Family Files. Separate logistic models were used to quantify the association between socioeconomic position, clinical risk factors and spontaneous preterm birth and iatrogenic preterm birth. Results The study population included 132,714 singleton deliveries and the rate of preterm birth was 5.5%. Preterm birth rates were significantly higher among the women in the lowest (versus the highest) family income group for spontaneous (rate ratio 1.14, 95% confidence interval (CI) 1.03, 1.25) but not iatrogenic preterm birth (rate ratio 0.95, 95% CI 0.75, 1.19). Adjustment for maternal characteristics attenuated the family income-spontaneous preterm birth relationship but strengthened the relationship with iatrogenic preterm birth. Clinical risk factors such as hypertension were differentially associated with spontaneous (rate ratio 3.92, 95% CI 3.47, 4.44) and iatrogenic preterm (rate ratio 14.1, 95% CI 11.4, 17.4) but factors such as diabetes mellitus were not (rate ratio 4.38, 95% CI 3.21, 5.99 for spontaneous and 4.02, 95% CI 2.07, 7.80 for iatrogenic preterm birth). Conclusions Socioeconomic position and clinical risk factors have different effects on spontaneous and iatrogenic preterm. Recent temporal increases in iatrogenic preterm birth appear to be responsible for the inconsistent relationship between socioeconomic position and preterm birth.

Background: Increased total homocysteine (tHcy) may be associated with placental-mediated adverse pregnancy outcomes, but few prospective studies have measured tHcy before pregnancy outcome. This study was undertaken to determine whether increased tHcy measured in early pregnancy is associated with pregnancy loss, gestational hypertension (GH), preeclampsia, or small for gestational age (SGA) infants. Methods: We conducted a prospective cohort study between 2002 and 2005. We measured tHcy and serum folate in blood samples from pregnant women (<20 weeks’ gestation) and collected detailed pregnancy information through a questionnaire and medical record review. Results: Of the 2119 women included in the study, 103 had a pregnancy loss, 115 had gestational hypertension, 65 had preeclampsia, and 129 had an SGA infant. Subjects with increased tHcy concentrations were at increased risk of pregnancy loss [relative risk (RR) 2.1, 95% CI 1.2–3.6] or preeclampsia (RR 2.7, 95% CI 1.4–5.0) than subjects with lower tHcy concentrations, but increased tHcy concentration was not associated with increased risk of developing GH or having an SGA infant. Conclusion: The finding of high tHcy in early pregnancy as a risk factor for pregnancy loss and preeclampsia is consistent with a hypothesis that increased tHcy results in abnormalities of the placental vasculature.

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 The mode of delivery has recently gained attention as another potential perinatal risk factor for childhood obesity but results are conflicting. Objective To examine whether caesarean section is independently associated with childhood obesity after adjusting for a broad range of confounding factors. Methods The current study used a population-based survey in Grade 5 students linked to a provincial perinatal registry in the Canadian province of Nova Scotia. Associations between caesarean section and childhood overweight and obesity at age 10/11 years were examined using multiple logistic regression. Results Of the 4298 students who participated in the 2003 Children's Lifestyle and School Performance Study (response rate 51.1%), 3426 (80%) could be linked with information in the Atlee Perinatal Database, and 2988 mother-child pairs (70%) had complete information on the exposure and outcome. Compared to vaginal delivery, caesarean section was associated with offspring obesity (OR) 1.49, 95% CI 1.10 to 2.00) in the univariate analysis. After adding maternal prepregnancy weight to the multiple regression model, the OR for obesity dropped from 1.48 to 1.20 (95% CI 0.87 to 1.65). When caesarean section with and without labour were considered separately, we found no statistically significant associations relative to the vaginal delivery group (OR 1.24, 95% CI 0.84 to 1.82 and OR 1.03, 95% CI 0.58 to 1.84). Conclusion Our results do not support a causal association between caesarean section and childhood obesity. Maternal prepregnancy weight was an important confounder in the association between caesarean delivery and childhood obesity and needs to be considered in future studies.

Animal studies and epidemiological evidence suggest an association between prenatal exposure to drinking water with elevated nitrate (NO3-N) concentrations and incidence of congenital anomalies. This study used Geographic Information Systems (GIS) to derive individual-level prenatal drinking-water nitrate exposure estimates from measured nitrate concentrations from 140 temporally monitored private wells and 6 municipal water supplies. Cases of major congenital anomalies in Kings County, Nova Scotia, Canada, between 1988 and 2006 were selected from province-wide population-based perinatal surveillance databases and matched to controls from the same databases. Unconditional multivariable logistic regression was performed to test for an association between drinking-water nitrate exposure and congenital anomalies after adjusting for clinically relevant risk factors. Employing all nitrate data there was a trend toward increased risk of congenital anomalies for increased nitrate exposure levels though this was not statistically significant. After stratification of the data by conception before or after folic acid supplementation, an increased risk of congenital anomalies for nitrate exposure of 1.5–5.56 mg/L (2.44; 1.05–5.66) and a trend toward increased risk for >5.56 mg/L (2.25; 0.92–5.52) was found. Though the study is likely underpowered, these results suggest that drinking-water nitrate exposure may contribute to increased risk of congenital anomalies at levels below the current Canadian maximum allowable concentration.

The birth prevalence of cerebral palsy varies over time among very preterm infants, and the reasons are poorly understood. To describe the variation in the prevalence of cerebral palsy among very preterm infants over time, and to relate these differences to other maternal or neonatal factors. A population-based cohort of very preterm infants was evaluated over a 20-year period (1988 to 2007) divided into four equal epochs. The prevalence of cerebral palsy peaked in the third epoch (1998 to 2002) while mortality rate peaked in the second epoch (1993 to 1997). Maternal anemia, tocolytic use and neonatal need for home oxygen were highest in the third epoch. Lower mortality rates did not correlate well with the prevalence of cerebral palsy. Maternal risk factors, anemia and tocolytic use, and the newborn need for home oxygen were highest during the same epoch as the peak prevalence of cerebral palsy.