Malik S et al. (2008) Maternal smoking and congenital heart defects. Pediatrics 121: e810–e816

The body of evidence linking fetal exposure to tobacco smoke to an increased risk of structural birth defects is substantial. Now, Malik et al. have conducted a population-based case–control study to obtain a better understanding of the associations between specific subtypes of congenital heart disease (CHD) and maternal smoking.

Overall, 3,067 women who gave birth to singleton infants with nonsyndromic CHD and 3,947 women who gave birth to singleton infants without birth defects were enrolled in the study. Among the infants with non-syndromic CHD, 40.1% had septal heart defects. Analyses stratified by CHD subtype identified a significant association between the risk of giving birth to an infant with a septal heart defect and periconceptional smoking. In comparison with women who did not smoke during this period, the risk of giving birth to an infant with a septal defect was 1.44 times higher among women who reported light periconceptional smoking (1–14 cigarettes per day) and 2.06 times higher among women who reported the heaviest levels of periconceptional smoking (at least 25 cigarettes a day), independent of maternal age, folic acid intake and ethnicity. In addition, the heaviest level of maternal smoking was associated with an increased risk of right-sided obstructive heart defects, particularly pulmonary valve stenosis (odds ratio 2.31, 95% CI 1.11–4.83). No association was found between maternal exposure to environmental tobacco smoke and risk of CHD.

These results strongly support the goals of the US Public Health Service, which hopes to achieve smoking abstinence in 98% of pregnant women by 2010.