Associations between PM2.5 exposure and birth outcomes and effect modification by extreme heat events during pregnancy in a North Carolina cohort

Background and aim Adverse birth outcomes, like term low birth weight (TLBW) and preterm birth (PTB), can be indicators for poor health outcomes, including neonatal mortality, and may be caused by environmental exposures. Previously, exposure to high ambient temperatures was linked with increased odds of TLBW, while results looking at fine particulate matter (PM2.5) exposure have been mixed. A growing body of studies report associations between PTB and air pollution. We evaluated the relationship between PM2.5 exposure during pregnancy and TLBW and PTB, and potential modification by concurrent exposure to extreme heat events (EHEs).

Impact/Purpose

We evaluated the associations between gestational exposure to PM2.5 and EHEs with TLBW and PTB during two time periods (2006-2009, 2011-2015) in a NC birth cohort. When examining each exposure independently, we observed generally null associations between both TLBW or PTB and PM2.5 exposure averaged over the entire pregnancy and each trimester. The strongest associations were for PTB and PM2.5 concentrations averaged over the entire pregnancy and second trimester. For the binary EHE exposure, we observed negative RD for entire pregnancy and third trimester, with higher RD in the later years compared to the earlier years. In co-exposure models, we observed positive RD for PM2.5 and both TLBW and PTB for PM2.5 adjusted for EHE during the entire pregnancy and third trimester. For co-exposure models in which EHEs were adjusted for PM2.5 concentrations, we observed similar patterns and magnitudes of association as those observed in the single pollutant models. Finally, there was no evidence of effect measure modification from interaction models of PM2.5 and EHE for either birth outcome during the earlier or later years of the study period.

Citation

Krajewski, A., B. Alman, A. Vaidyanathan, J. Warren, Tom Luben, AND K. Rappazzo. Associations between PM2.5 exposure and birth outcomes and effect modification by extreme heat events during pregnancy in a North Carolina cohort. Elsevier B.V., Amsterdam, NETHERLANDS, 362:121500, (2025). [DOI: 10.1016/j.atmosenv.2025.121500]

DOI: Associations between PM2.5 exposure and birth outcomes and effect modification by extreme heat events during pregnancy in a North Carolina cohort