Prenatal Exposure to PM 2.5 and Its Specific Components and Risk of Hypertensive Disorders in Pregnancy: A Nationwide Cohort Study in China.

Hypertensive disorders in pregnancy (HDP) are a leading cause of maternal mortality and adverse birth outcomes. Fine particulate matter (PM 2.5 ) has been linked to HDP risk; however, limited studies have explored the relationships between specific chemical constituents of PM 2.5 and HDP risk. Based on maternal data from the China Labor and Delivery Survey (CLDS), this study included a total of 67,659 participants from 95 participant hospitals in 25 provinces of China between March 1, 2015, and December 31, 2016. Maternal exposure to total PM 2.5 mass and six main components during pregestation and pregnancy were estimated using the Combined Geoscience-Statistical Method. Multilevel logistic regression models were applied to quantify the associations, controlling for sociodemographic characteristics. We found that an interquartile range (IQR) increase in PM 2.5 exposure during the second trimester was associated with a 14% increase in HDP risk (95% CI: 2%, 29%). We observed that black carbon (BC) and SO 4 2- had larger or comparable estimates of the effect than total PM 2.5 mass. The association estimates were greater in the gestational hypertension group than in the group of pre-eclampsia and eclampsia. Our findings suggest that PM 2.5 exposure and specific chemical components (particularly BC and SO 4 2- ) were associated with an increased HDP risk in China.