Background
The association between active maternal smoking and congenital malformations is well established, but little is known about the association between secondhand smoke and congenital malformations. Moreover, studies regarding the association between congenital malformations and secondhand smoke have not yielded consistent results.
Methods
In July 2018, we searched PubMed, EMBASE, and China Biology Medicine databases for observational studies characterizing the relationship between secondhand smoke and congenital malformations of offspring in nonsmoking women. Two reviewers independently decided on whether a study should be included, did data extraction, and assessed study quality. Pooled risks with 95% confidence intervals were calculated using either the fixed‐effects models or random‐effects models. Further subgroup analyses and sensitivity analyses were performed to explore the potential source of heterogeneity and to examine the robustness of risk estimates.
Results
Thirty‐three studies with a total of 31 944 cases and 32 335 controls were included. Secondhand smoke exposure was associated with an increased risk of congenital malformations (odds ratio = 1.92; 95% confidence interval 1.61‐2.30). Secondhand smoke was correlated with significantly increased risk for digestive system (1.17 [1.05‐1.32]), nervous system (1.74 [1.33‐2.29]), and cardiovascular system (2.10 [1.32‐3.35]) malformations and for oral clefts (1.87 [1.47‐2.39]).
Conclusions
Secondhand smoke exposure increases the risk for overall and several organ‐system malformations. These findings highlight the necessity of improving community awareness to prevent secondhand smoke exposure during the preconception and conception periods.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.