Small vulnerable newborns and prenatal exposure to organophosphate esters: Insights from the Ma'anshan Birth Cohort.

Evidence on the association between prenatal exposure to organophosphate ester (OPE) and small vulnerable newborn components is limited and inconsistent. This study included 3208 mother-child dyads from the Ma'anshan Birth Cohort. In the first, second, and third trimesters, urine samples were used to detect 6 OPE metabolites to reduce misclassification bias in exposure. Statistical models, including robust poisson regression and quantile g-computation model, were used to explore the associations of OPE exposure with small vulnerable newborns and their component variables and the co-exposure effects, respectively. Poisson regression analysis revealed that exposure to tris(2-chloroethyl) phosphate (TCEP) during the first trimester and diphenyl phosphate (DPHP) during the third trimester were associated with a decreased risk of small vulnerable newborns [risk ratio (RR) = 0.68, 95% confidence interval (CI): 0.49, 0.94 for TCEP; RR= 0.85, 95%CI: 0.75, 0.97 for DPHP), mirroring the results obtained from the mixture exposure analysis. This inverse relationship may inherently reflect an underlying phenomenon of prolonged gestational duration and increased birth weight. The study first explored the impact of prenatal exposure to OPEs on the entire small vulnerable newborns, suggesting that prenatal OPEs have sex- and trimester-specific effects on the risk of small vulnerable newborns. The analysis results of OPE for different small vulnerable newborn component variables also verified the complex relationship between OPE and adverse birth outcomes.