Prenatal exposure to wildfire fine particulate matter and fetal growth outcomes in the United States: Findings from the ECHO Cohort

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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Publication Details

Journal
Environmental Epidemiology
Published
2026-09-09
DOI
https://doi.org/10.1097/ee9.0000000000000526
Primary Topic
Air Quality and Health Impacts
Type
article
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article

Prenatal exposure to wildfire fine particulate matter and fetal growth outcomes in the United States: Findings from the ECHO Cohort

Daphne Koinis‐Mitchell, Alicia K. Peterson, Alison Gemmill, Thomas G. O’Connor et al.
Environmental Epidemiology
Air Quality and Health Impacts
article

Prenatal exposure to wildfire fine particulate matter and fetal growth outcomes in the United States: Findings from the ECHO Cohort

Daphne Koinis‐Mitchell, Alicia K. Peterson, Alison Gemmill, Thomas G. O’Connor, Hooman Mirzakhani, Logan C. Dearborn, Marissa L. Childs, R. Morello-Frosch, Leslie D. Leve, Christine T. Loftus, Lisa Croen, Rebecca J. Schmidt, Dana E. Goin, Miatta A. Buxton, Amii Kress, Adam A. Szpiro, Allison R. Sherris, Donghai Liang, Erika Garcia, Alison E. Hipwell, Jyoti Angal, Catherine J. Karr, Sindana D. Ilango, Kristen Lyall, Cindy T. McEvoy, Shohreh F. Farzan, Irva Hertz‐Picciotto, Deborah H. Bennett, Kecia N. Carroll, Deborah Hirtz, Lacey A. McCormack, Zhongzheng Niu, Stephanie M. Eick, Joan A. Casey (5172998), Camille Cioffi, Assiamira Ferrara, Amy M. Padula, Carlos A. Camargo, Rima Habre, Frank Gilliland, Dana Dabelea, Margaret R. Karagas
article en

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.

Environmental EpidemiologyVol. 10(5)
Dartmouth College (US), University of Vermont (US), University of Southern California (US), Brigham and Women's Hospital (US), Kaiser Permanente (US), Harvard University (US), Johns Hopkins University (US), Emory University (US), Oregon Health & Science University (US), University of Pittsburgh (US), University of California, San Francisco (US), University of Oregon (US), University of South Dakota (US), University of Washington (US), Brown University (US), University of Michigan (US), Massachusetts General Hospital (US), Berkeley Public Health Division (US), Avera McKennan Hospital & University Health Center (US), University of Colorado Anschutz Medical Campus (US), University of Rochester (US), Drexel University (US), Columbia University (US), University of California, Davis (US), University of California, Berkeley (US), Icahn School of Medicine at Mount Sinai (US)
No poverty
Openalex Percentile: Top 12%
Air Quality and Health Impacts
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