Mediating effects of gut microbiota in the associations of air pollutants exposure with adverse pregnancy outcomes

The aim of this study was to investigate alterations in gut microbiota after exposure to air pollutants during pregnancy and its mediation effect in inducing adverse pregnancy outcomes (APOs). Participants (n = 916) were enrolled between 2017 and 2018 from a prospective cohort study of pregnant women in Guangzhou, China. The relative abundance of fecal microbiota was profiled using 16SrRNA V4 region sequencing. Exposure to air pollutants in each trimester of pregnancy was assessed using measurements from the nearest monitoring station. APOs including pre-term birth (PTB), post-term birth (POTB), low birth weight (LBW), macrosomia fetus (MF), birth defects (BDs), pathological cesarean section (PCS) and postpartum hemorrhage (PPH)) were determined by referring to reliable clinical records and diagnostic criteria. Univariate analysis, multivariate analysis and mediation analysis were performed to estimate the association among air pollutants, gut microbiota and APOs. Air pollutants exposure during pregnancy was significantly correlated with the alterations in the gut microbiota, and increased risks of various APOs by 1.07–1.36-fold (P