UW News

Sindana Ilango


November 3, 2025

UW-led study links wildfire smoke to increased odds of preterm birth

A thin haze of wildfire smoke covers downtown Seattle.

In mid-pregnancy, exposure to any smoke was associated with an elevated risk of preterm birth, with that risk peaking around the 21st week of gestation. In late pregnancy, elevated risk was most closely associated with exposure to high concentrations of wildfire PM2.5, above 10 micrograms per cubic meter.