Prenatal exposure to multiple air pollutants and risks of preterm birth and low birth weight in twins: A comparison between natural conception and medically assisted reproduction.

Exposure to air pollution has been linked to higher risks of adverse pregnancy outcomes. However, evidence from twin pregnancies is limited, and differences between natural conception (NC) and medically assisted reproduction (MAR) remain unexplored. This study enrolled 935 twin pairs in Wuxi, China, from 2017 to 2022. A high spatiotemporal resolution prediction model was used to assess prenatal exposure to air pollutants, including PM2.5, PM10, SO2, NO2, CO, and O3. Associations of prenatal air pollution exposure with preterm birth (PTB), low birth weight (LBW), and low birth weight preterm birth (LBWPT) were analyzed using generalized linear models. The prevalence of PTB, LBW, and LBWPT among the twin pairs was 68.0 %, 72.4 %, and 57.5 %, respectively. Prenatal exposures to PM2.5, PM10, SO2, and CO were significantly associated with increased risks of PTB, LBW, and LBWPT. Subgroup analyses revealed increased risks in the MAR group (SO2) for PTB and LBWPT, the NC group (CO) for LBW, and twins born in winter/spring (PM2.5, PM10, SO2) for PTB and LBWPT. Our findings underscore the importance of tailoring preventive measures to MAR-conceived twins, NC twins, and those born in winter/spring to better protect against the adverse effects of prenatal air pollution exposure.