Maternal placental growth factor mediates the association between PM2.5 and its constituents with adverse pregnancy outcomes.

Maternal placental growth factor (PLGF) is essential for fetal growth, and emerging evidence links PM2.5 exposure to adverse pregnancy outcomes (APOs). However, the effects of specific PM2.5 constituents on maternal PLGF levels and their underlying mechanism remain unclear. We recruited 11,677 mother-child pairs between 2017 and 2023 in Tianjin, China. Individual exposure was assessed using the Tracking Air Pollution in China dataset. Cox proportional hazards models and quantile-based g-computation models were utilized to assess the individual and joint effects of exposure to PM2.5 and its constituents on APOs. Causal mediation analysis was used to estimate the mediation effects of maternal PLGF levels on these association. Maternal exposure to PM2.5 and its constituents was associated with an increased risk of premature rupture of membrane, preterm birth (PTB), and low birth weight (LBW) during entire pregnancy. Among the constituents, organic matter (OM) demonstrated the greatest adverse effect. Causal mediation analysis indicated that decrease in maternal PLGF levels mediate by 30.4 % and 34.3 % of the associations between PM2.5 and PTB, LBW, respectively. Our findings highlighted the potential mechanism between PM2.5 and its constituents exposure and APOs by maternal PLGF as clinical biomarker reflecting placental function.