Wildfire Smoke Identified as Leading Pregnancy Pollutant in U.S. Study

A 16‑year study of about 64.5 million pregnancies across 2,800 counties in 48 U.S. states found that while overall air‑pollution from cars and industry has declined, wildfire smoke has become the primary pollutant linked to adverse pregnancy outcomes. The analysis showed that roughly 65 % of days exceeding the National Ambient Air Quality Standard were attributable to wildfire smoke, and the exposure was associated with higher rates of low birth weight and preterm births.

Lead author Menglu Liang, an assistant clinical professor of biostatistics at the University of Maryland, said the findings highlight how recent increases in wildfire smoke are offsetting decades of progress in air‑quality improvements. The study period ends in 2019 and does not cover the most severe recent fire seasons, including the 2020, 2024 and 2026 outbreaks that have produced hundreds of wildfires across Canada and the western United States, with Oregon experiencing its worst season on record.

The research underscores growing public‑health concerns as climate‑driven fire activity intensifies, suggesting a need for targeted protections for pregnant people in smoke‑affected regions.