Abstract 3274: Congenital Heart Disease and Maternal Smoking
Introduction: In a population-based case-control study, we investigated the association between congenital heart disease (CHD) and maternal smoking.
Methods: In collaboration with the National Birth Defects Prevention Study, we enrolled 566 infants with nonsyndromic CHDs and their parents, and 491 infants without birth defects and their parents. Affected infants had one of more of the following defects: conotruncal, left and/or right-sided obstructive and/or septal heart defect. Mothers of cases and controls were asked if they smoked from 1 month prior to pregnancy through the first trimester. Maternal home and workplace exposure to tobacco smoke during the same period was determined. Logistic regression was used to compute odds ratios and 95% confidence intervals while controlling for potential confounders.
Results: Cases were more likely to be premature and have lower birth weight than controls. Women who had infants with CHDs were more likely to have smoked anytime during the month before pregnancy to the end of the first trimester (34%) than women who had infants without birth defects (25%; OR 1.6; 95% CI 1.2–2.1). This relationship was independent of potential confounding factors, including prenatal vitamin use, alcohol intake, maternal age, and race/ethnicity. In subgroup analysis, the risk of CHD remained significant for septal (OR 1.8; 95% CI 1.1–3.1) and right-sided obstructive (OR 1.8, 95% CI 1.2–2.5) defects. Mothers who had an infant with a CHD were also more likely to have been exposed at home or workplace to tobacco smoke from 1 month prior to pregnancy through the first trimester (OR 1.3, 95% CI 1.01–1.7).
Conclusion: Maternal smoking and tobacco exposure during pregnancy are associated with an increased risk of CHD, especially septal and right-sided obstructive defects. Further investigation into the timing of tobacco exposure and genetic susceptibilities that may modify the risk will provide a more precise evidence-base on which to build clinical and public health primary prevention strategies.