Abstract P140: Maternal Smoking During Pregnancy and Risk of Congenital Heart Defects: A Systematic Review and A Meta-Analysis
Objective: Congenital heart defects (CHDs) are the most common group of structural malformations occurring in approximately 1 out of every 100 births. In addition to being the most prevalent birth defect, CHDs are the leading cause of death due to congenital malformations. Despite their prevalence and clinical importance, little is known about the etiology of CHDs, and there are currently no strategies for reducing their prevalence. Maternal smoking during pregnancy has been suggested as a potential risk factor for congenital heart defects, but the evidence is inconclusive. We systematically reviewed epidemiological studies and conducted a meta-analysis of the association between maternal cigarette smoking during pregnancy and the risk of CHDs among the infants.
Methods: From a search of published literature through July 2011, we extracted 35 original human epidemiological studies that examined the association between maternal smoking during pregnancy (including a month before conception) and the risk of CHDs in offspring. Odds ratios (ORs) and 95% confidence intervals (CIs) were extracted from each study or calculated from available data, comparing smoking to no smoking during pregnancy. Summary risk estimates were also calculated for a number of CHDs subtypes (e.g., conotruncal defects, ventricular septal defects) using both fixed- and random-effects models. Random effects estimates were reported if there was evidence of heterogeneity among the studies. Effects of paternal and environmental smoking were not considered in our analysis.
Results: We observed statistically significant positive association between maternal smoking anytime during pregnancy and the risk of CHDs (OR = 1.10; 95% CI: 1.01–1.19; number of cases (n) = 19,552). Additionally, we found a positive and significant association between maternal smoking and the risk of conotruncal defects in offspring (OR = 1.14; 95% CI: 1.03–1.26; n = 1953). Although not statistically significant, stronger elevated risks were observed for ventricular septal defects (OR = 1.11; 95% CI: 0.87–1.41; n = 4605) and atrial septal defects (OR = 1.34; 95% CI: 0.97–1.86; n = 565).
Conclusion: Our systematic review and meta-analysis suggest maternal smoking is modestly associated with an increased risk of CHDs and some CHDs subtypes. This work adds to the existing body of evidence that implicated maternal smoking during pregnancy as a possible risk factor for CHDs. Future studies should consider evaluating paternal and environmental smoking exposure to better understand the relationship between smoking and CHDs.
- © 2012 by American Heart Association, Inc.