Background: Maternal smoking has been consistently associated with increased risk of cleft lip with or without cleft palate (CL/P). Few studies have explored the possible effect of passive smoking. We examined the association between maternal passive smoking and the risk of CL/P among nonsmoking women in China.
Methods: Subjects included 88 infants with CL/P and 651 infants with no major external birth defects. Data were collected by trained health workers through face-to-face interviews.
Results: The odds ratio (OR) for CL/P associated with maternal passive smoking was 1.8 (95% confidence interval = 1.1–2.8). After adjustment for maternal occupation, periconceptional flu or fever, and infant sex, the risk was 2.0 (1.2–3.4). The adjusted ORs for exposure levels of 1–6 times per week and more than 6 times per week (at least 1 cigarette each time) were 1.6 (0.9–2.9) and 2.8 (1.5–5.2), respectively.
Conclusion: Maternal passive smoking during pregnancy was associated with an increased risk for CL/P in offspring.