Adverse associations of pre-pregnancy exposure to PM and its components with fetal growth alleviated by residential greenness: a prospective cohort study.

Maternal exposure to fine particulate matter (PM) and residential greenness both influence fetal growth. No previous studies have examined their sex-specific and interaction effects. We aim to evaluate the sex-specific effects in these associations and exposure interactions. This study involved 1,275 mother-child pairs enrolled in the Ma'anshan birth cohort in China. Pre-pregnancy exposure to PM and its components was assessed using a spatiotemporal model based on maternal addresses, while residential greenness was estimated through the normalized difference vegetation index (NDVI) based on satellite data. Fetal parameters-including biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), and estimated fetal weight (EFW)-were measured during pregnancy via ultrasound. To examine associations between these exposures and both continuous and categorical outcomes, generalized estimating equations (GEE) and generalized linear regression were applied. Subgroup analyses were conducted to evaluate sex-specific effects. Pre-pregnancy exposure to PM, OM, BC, SO, NH, and NO was correlated with decreased Z-scores of fetal parameters (BPD, FL, EFW, AC) during the second trimester, particularly in male fetuses. In the third trimester, we found that the Z-scores of AC (0.081, 95% CI: 0.001, 0.160) and EFW (0.097, 95% CI: 0.008, 0.185) increased with each interquartile range (IQR) increase in residential greenness. We observed the effect modification of PM and its components on the relationship between residential greenness and fetal growth in utero. Residential greenness can mitigate the adverse effects of PM and its components prior to pregnancy on fetal growth. Our findings suggest that increased residential greenness during pregnancy preparation may help alleviate air pollution's detrimental effects on fetal growth.