Parental Smoking and the Risk of Birth Defects in Offspring in China: A Systematic Review and meta-Analysis

A meta-analysis of case-control studies was conducted to assess the risk of birth defects in offspring in China associated with maternal active and passive smoking and paternal smoking.

Four electronic databases were searched for qualified research up to December 2023. A Random-effect model or fixed-effect model was used to calculate the overall comprehensive risk estimates; and the relationship between parental smoking and the risk of birth defects in different periods of pregnancy. Subgroup and sensitivity analyses were performed to explore possible sources of heterogeneity.

Sixty-two qualified studies involving 137,574 cases and 8,770,837 controls were included. Overall, maternal active smoking (OR = 2.19; 95% confidence interval (CI): 1.72-2.79; p < 0.01) and passive smoking (OR = 2.59,95% CI: 2.24-2.99; p < 0.01) as well as paternal active smoking (OR = 1.47,95% CI: 1.34-1.62; p < 0.01) were significantly associated with birth defect risk. The sources of heterogeneity were explored by subgroup analysis. Subgroup analysis showed that the risk of congenital heart disease in offspring was increased in paternal and maternal active smoking (OR = 2.97, 95% CI: 2.01-4.39; OR = 1.51, 95% CI: 1.30-1.74), respectively. Sensitivity analysis yielded consistent results.

Maternal active and passive smoking and paternal active smoking are risk factors for birth defects in offspring. Parents should be encouraged to quit smoking during the perinatal period and pregnancy.