Gestational Exposure to PM2.5 and Specific Constituents, Meconium Metabolites, and Neonatal Neurobehavioral Development: A Cohort Study

Exposure to fine particulate matter (PM_2.5) during pregnancy has been inversely associated with neonatal neurological development. However, the associations of exposure to specific PM_2.5 constituents with neonatal neurological development remain unclear. We investigated these associations and examined the mediating role of meconium metabolites in a Chinese birth cohort consisting of 294 mother–infant pairs. Our results revealed that exposure to PM_2.5 and its specific constituents (i.e., organic matter, black carbon, sulfate, nitrate, and ammonium) in the second trimester, but not in the first or third trimester, was inversely associated with the total neonatal behavioral neurological assessment (NBNA) scores. The PM_2.5 constituent mixture in the second trimester was also inversely associated with NBNA scores, and sulfate was identified as the largest contributor. Furthermore, meconium metabolome analysis identified four metabolites, namely, threonine, lysine, leucine, and saccharopine, that were associated with both PM_2.5 constituents and NBNA scores. Threonine was identified as an important mediator, accounting for a considerable proportion (14.53–15.33%) of the observed inverse associations. Our findings suggest that maternal exposure to PM_2.5 and specific constituents may adversely affect neonatal behavioral development, in which meconium metabolites may play a mediating role.