Maternal Smoking and Congenital Heart Defects, National Birth Defects Prevention Study, 1997-2011

Objectives To assess associations between maternal smoking and congenital heart defects (CHDs) in offspring. Study design We performed a retrospective case-control study using data for cases of CHD (n = 8339) and non-malformed controls (n = 11 020) from all years (1997-2011) of the National Birth Defects Prevention Study. Maternal self-reported smoking 1 month before through 3 months after conception was evaluated as a binary (none, any) and categorical (light, medium, heavy) exposure. Multivariable logistic regression was used to estimate aOR and 95% Cls. Stratified analyses were performed for septal defects according to maternal age, prepregnancy body mass index, and maternal race/ethnicity. Results Multiple CHDs displayed modest associations with any level of maternal periconceptional smoking independent of potential confounders; the strongest associations were for aggregated septal defects (OR, 1.5; 95% CI, 1.3-1.7), tricuspid atresia (OR, 1.7; 95% CI, 1.0-2.7), and double outlet right ventricle (DORV) (OR, 1.5; 95% CI, 1.1-2.1). Tricuspid atresia and DORV also displayed dose-response relationships. Among heavy smokers, the highest odds were again observed for tricuspid atresia (aOR 3.0; 95% CI, 1.5-6.1) and DORV (aOR 1.5; 95% CI, 1.1-2.2). Heavy smokers >= 35 years old more frequently had a child with a septal defect when compared with similarly aged nonsmokers (aOR 2.3; 95% CI, 1.4-3.9). Conclusions Maternal periconceptional smoking is most strongly associated with septal defects, tricuspid atresia, and DORV; the risk for septal defects is modified by maternal age.

Automated summary

Maternal periconceptional smoking is strongly associated with septal defects, tricuspid atresia, and double outlet right ventricle (DORV). The risk is higher for heavy smokers, with the highest odds observed for tricuspid atresia and DORV. Maternal age also modifies the risk for septal defects, with heavy smokers above 35 years old having a higher likelihood of having a child with a septal defect compared to similarly aged nonsmokers.