Effects of prenatal pyrethroid pesticides exposure on neurodevelopment of 3-year-old children: A birth cohort study in rural Southwest China.

Widespread exposure to pyrethroid pesticides (PYRs) has emerged as a critical public health concern, yet the longitudinal impact of prenatal exposure windows on early childhood neurodevelopment remains to be fully elucidated. This birth cohort study in rural Southwest China investigated 308 mother-child pairs to assess the effects of maternal PYRs exposure across all three trimesters on neurodevelopment at 3 years of age. Urinary metabolites (3-PBA, 4F-3-PBA, and cis-DBCA) were quantified via UHPLC-MS/MS, and neurodevelopment was evaluated using the Bayley Scales of Infant and Toddler Development, 3rd edition (BSID-III). Our findings revealed that elevated maternal 4F-3-PBA levels during the second and third trimesters were significantly associated with decreased Cognition and Adaptive Behavior scores. Importantly, cross-trimester interaction analysis corroborated the third trimester as a uniquely sensitive window for specific metabolites, where late-gestational 3-PBA and cis-DBCA exposures were transitionally tied to reduced Social-Emotional and motor scores, respectively. Furthermore, third-trimester cis-DBCA exposure was inversely correlated with Cognition, Language, and Motor performances. Mid-to-late gestational 4F-3-PBA low-level exposure significantly increased the risks of Adaptive Behavior and Language delays, whereas first-trimester cis-DBCA low-level exposure elevated the risk of Adaptive Behavior delay. Additionally, formal interaction analysis suggested potential sex-specific patterns, with the adverse neurodevelopmental impacts appearing more pronounced in male offspring. These results highlight the window-specific and suggestive sex-differential neurotoxicity of low-level prenatal PYRs exposure and underscore the importance of monitoring pesticide exposure during critical gestational windows to mitigate long-term developmental risks.