Maternal exposure to fine particulate matter before and during pregnancy, and the risk of birth defects: A population-based study.

Although epidemiological evidence has linked maternal exposure to air pollution with adverse birth outcomes, the association between exposure to fine particulate matter (PM) and the risk of total birth defects in highly polluted developing regions remains limited. The objective of this study was to assess the relationship between maternal exposure to PM before and during pregnancy and the occurrence of birth defects. This study included 16,080 births with birth defects and 567,483 controls born between 2014 and 2019 in 14 cities in Liaoning Province, China. The assessment of exposure was conducted using satellite-based PM data at a spatial resolution of 1 km. Participants were classified into four subgroups based on their exposure to PM before and during pregnancy. The association between maternal exposure to PM, and the risk of birth defects, was estimated using logistic regression models. For each 10 μg/m³ increase in PM, the odds ratios of birth defects were 1.68 (95% CI: 1.65, 1.70) and 2.41 (95% CI: 2.36, 2.45) during the preconception period and pregnancy, respectively. We observed a J-shaped association between maternal PM exposure during both the preconception period and pregnancy and the risk of total birth defects. Mothers exposed to elevated levels of PM during both the preconception period and pregnancy exhibited the highest risk of total birth defects (odds ratio: 4.43, 95% CI: 4.17, 4.71). Our findings illustrated that maternal exposure to PM before and during pregnancy was associated with increased risks of birth defects and underscored the potential health benefits of reducing air pollution exposure during the preconception period and pregnancy.