Prenatal exposure to wildfire fine particulate matter and fetal growth outcomes in the United States: Findings from the ECHO Cohort
Abstract
Background: Increasing exposure to wildfire fine particulate matter (PM 2.5 ) may pose unique risks to fetal development. We assessed associations between prenatal wildfire PM 2.5 exposure and fetal growth outcomes, including birth weight at term, birth weight for gestational age z -scores, small for gestational age, and large for gestational age in the U.S. Environmental Influences on Child Health Outcomes Cohort. Methods: The study included 20,034 births (2006–2020) from 30 cohort sites nationwide. We assigned daily wildfire PM 2.5 at census-tract resolution and summarized average concentrations and the number of smoke days exceeding multiple intensity thresholds across pregnancy. We used covariate-adjusted mixed-effects models to estimate overall associations and distributed lag models and trimester-specific analyses to evaluate critical exposure windows across gestation, and we examined potential effect modification by US region, fetal sex, maternal race, and neighborhood poverty. Results: Pregnancy wildfire exposure metrics, including mean prenatal PM 2.5 and the number of smoke days, were not associated with study outcomes. Distributed lag and trimester-specific models did not show consistent sensitive windows of exposure associated with birth weight at term, birth weight for gestational age z -scores, or small for gestational age. A positive association was observed between higher early-pregnancy wildfire exposure and large for gestational age (odds ratio = 1.015 per smoke day, 95% confidence interval: 1.001, 1.029), though effect estimates were small in magnitude. No consistent effect modification was identified. Conclusion: In this nationwide cohort, wildfire PM 2.5 showed limited associations with fetal growth outcomes.
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Authors: Allison R. Sherris, Logan C. Dearborn, Dana E. Goin, Christine T. Loftus, Adam A. Szpiro, Joan A. Casey (5172998), Sindana D. Ilango, Jyoti Angal, Deborah H. Bennett, Miatta A. Buxton, Carlos A. Camargo, Kecia N. Carroll, Marissa L. Childs, Camille Cioffi, Lisa Croen, Dana Dabelea, Stephanie M. Eick, Shohreh F. Farzan, Assiamira Ferrara, Erika Garcia, Alison Gemmill, Frank Gilliland, Rima Habre, Irva Hertz‐Picciotto, Alison E. Hipwell, Deborah Hirtz, Margaret R. Karagas, Daphne Koinis‐Mitchell, Amii Kress, Leslie D. Leve, Donghai Liang, Kristen Lyall, Lacey A. McCormack, Cindy T. McEvoy, Hooman Mirzakhani, R. Morello-Frosch, Zhongzheng Niu, Thomas G. O’Connor, Alicia K. Peterson, Rebecca J. Schmidt, Catherine J. Karr, Amy M. Padula
Institutions: Brigham and Women's Hospital, University of Pittsburgh, University of Washington, University of Rochester, University of Colorado Anschutz, Columbia University, Icahn School of Medicine at Mount Sinai, Johns Hopkins University, Harvard University, Brown University, University of California, San Francisco, University of Michigan, Oregon Health & Science University, Emory University, University of Southern California, Drexel University, Dartmouth College, University of Vermont, University of California, Berkeley, Massachusetts General Hospital, University of California, Davis, University of Oregon, Kaiser Permanente, University of South Dakota, Avera McKennan Hospital & University Health Center, Berkeley Public Health Division