The association between air pollution exposure during pregnancy and low birth weight: a retrospective cohort study in southern China

To explore the association between individual and mixed exposure to air pollutants during pregnancy and low birth weight (LBW), and refine the susceptible exposure windows of LBW caused by air pollution exposure during pregnancy. A total of 41,397 pairs of mothers and infants were collected from the neonatal birth records registered by the Obstetrics Department of Fujian Provincial Maternal and Child Health Hospital from 2015 to 2019, including 1,532 cases of LBW newborns. The Logistic regression model was used to explore the association between individual exposure to air pollutants and LBW in different gestational periods. Further combining Distributed lag nonlinear model (DLNM) to explore exposed week of air pollution and vulnerable window period of LBW. The association between co-exposure to air pollutants and LBW was explored by using the dual-pollutant model and Weighted quantile sum (WQS) regression. The full trimester PM 2.5 and CO exposures were associated with increased odds of LBW (OR = 1.022, 95%CI: 1.002–1.042 and OR = 1.014, 95%CI: 1.001–1.027, respectively). Among pregnant women under the age of 35 years, the exposure levels of PM 2.5 and CO were associated with higher odds of LBW, while among pregnant women with gestational diabetes, PM 2.5 , PM 10 and SO 2 exposure levels were also positively associated with higher odds of LBW. The WQS model indicates that mixed exposure to air pollution in the first trimester, the second trimester, and full trimester is associated with higher odds of LBW. The air pollutants that contribute the most to LBW are PM 2.5 and CO. PM 2.5 and CO exposure during pregnancy were associated with higher odds of LBW when exposed to single pollutants. Among which the air pollutants that contribute the most to LBW are PM 2.5 and CO. Future research needs to focus on the synergistic effect of multiple pollutants, to provide a basis for precise protection of maternal and infant health.