Maternal smoking and congenital heart defects in the Baltimore-Washington Infant Study

We investigated associations between maternal cigarette smoking during the first trimester and the risk of congenital heart defects (CHDs) among the infants. The Baltimore-Washington Infant Study was the first population-based case-control study of CHDs conducted in the United States. Case and control infants were enrolled during the period 1981-1989. We excluded mothers with overt pregestational diabetes and case mothers whose infants had noncardiac anomalies (with the exception of atrioventricular septal defects with Down syndrome) from the analysis, which resulted in 2525 case and 3435 control infants. Self-reported first-trimester maternal cigarette consumption was ascertained via an in-person interview after delivery. Associations for 26 different groups of CHDs with maternal cigarette consumption were estimated by using logistic regression models. Odds ratios (ORs) corresponded to a 20-cigarette-per-day increase in consumption. We observed statistically significant positive associations between self-reported first-trimester maternal cigarette consumption and the risk of secundum-type atrial septal defects (OR: 1.36 [95% confidence interval (CI): 1.04-1.78]), right ventricular outflow tract defects (OR: 1.32 [95% CI: 1.06-1.65]), pulmonary valve stenosis (OR: 1.35 [95% CI: 1.05-1.74]), truncus arteriosus (OR: 1.90 [95% CI: 1.04-3.45]), and levo-transposition of the great arteries (OR: 1.79 [95% CI: 1.04-3.10]). A suggestive association was observed for atrioventricular septal defects among infants without Down syndrome (OR: 1.50 [95% CI: 0.99-2.29]). These findings add to the existing body of evidence that implicates first-trimester maternal cigarette smoking as a modest risk factor for select CHD phenotypes.