Wildfire Smoke Exposure Raises Preterm Birth Risk by 7% Per Unit, Highlighting Summer Pregnancy Health Dangers

Wildfire smoke — one of the fastest-growing sources of air pollution in the United States — significantly increases the risk of preterm birth, with exposure during the second trimester posing the greatest danger, according to a landmark University of Washington study that analyzed more than 20,000 births across the contiguous United States.

The findings are not theoretical. With wildfire season beginning across the Western United States and smoke regularly reaching cities from coast to coast, millions of pregnant women will face smoke exposure this summer. Researchers say the evidence is now strong enough to prompt tailored public health messaging and immediate protective action for pregnant people during smoke events.