Association between ambient PM2.5 exposure during pregnancy and risk of preterm birth: a retrospective birth cohort study in Chengdu, Southwest China
Background Prenatal PM2.5 exposure has been associated with preterm birth (PTB), but evidence on exposure windows and population heterogeneity remain inconsistent. Methods This retrospective cohort included 35,136 singleton births at a Chengdu hospital from 2015 to 2024. Satellite- and monitor-based PM2.5 exposures wer...