Uploaded November 2025 | Updated September 2026, 2 weeks ago
A nationwide study sheds new light on the risks wildfire smoke poses to pregnant women and their fetuses.
“We found that there was a higher risk of preterm birth with higher exposure to wildfire smoke,” said co-author and UW Medicine pediatric environmental-medicine specialist Dr. Catherine Karr. “Unfortunately, in the western United States, that's where we saw the highest risk.”
Drawing on data from more than 20,000 women, the researchers found that nearly everyone was exposed to wildfire smoke at some point during pregnancy. Karr said even a small rise in levels of air pollution was associated with a 7% increased risk of preterm birth.
“Preterm birth has been increasing over time. It affects about 10% of pregnancies in the U.S. As a pediatrician, I am concerned because children who are born preterm are more likely to have long lasting health consequences,” she said.
Recognizing the growing threat, Karr urges those who are pregnant to monitor the Air Quality Index and to take precautions when levels reach unhealthy ranges. Practical steps include staying indoors during heavy smoke days, remaining in clean air spaces when possible, and avoid creating indoor pollutants by lighting candles and frying food.
A nationwide study sheds new light on the risks wildfire smoke poses to pregnant women and their fetuses.
“We found that there was a higher risk of preterm birth with higher exposure to wildfire smoke,” said co-author and UW Medicine pediatric environmental-medicine specialist Dr. Catherine Karr. “Unfortunately, in the western United States, that's where we saw the highest risk.”
Drawing on data from more than 20,000 women, the researchers found that nearly everyone was exposed to wildfire smoke at some point during pregnancy. Karr said even a small rise in levels of air pollution was associated with a 7% increased risk of preterm birth.
“Preterm birth has been increasing over time. It affects about 10% of pregnancies in the U.S. As a pediatrician, I am concerned because children who are born preterm are more likely to have long lasting health consequences,” she said.
Recognizing the growing threat, Karr urges those who are pregnant to monitor the Air Quality Index and to take precautions when levels reach unhealthy ranges. Practical steps include staying indoors during heavy smoke days, remaining in clean air spaces when possible, and avoid creating indoor pollutants by lighting candles and frying food.
