A large study led by the University of Washington, published in The Lancet Planetary Health, has found that people exposed to wildfire smoke during pregnancy are more likely to give birth prematurely.
The research analyzed more than 20,000 births across the U.S. between 2006 and 2020.
Air pollution and premature births
Preterm birth, defined as delivery before 37 weeks of pregnancy, affects roughly one in ten babies born in the United States.
It can lead to serious health challenges, both immediately after birth and later in life.
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"Preventing preterm birth really pays off with lasting benefits for future health" said Allison Sherris, lead author and UW postdoctoral researcher in environmental and occupational health sciences, to Medicalxpress.
She noted that while the causes of preterm birth remain complex, air pollution is a known risk factor, and wildfire smoke appears to play an important part.
How smoke exposure affects pregnancy
Researchers examined exposure to fine particulate matter, known as PM2.5, produced by wildfires.
These particles are small enough to be inhaled deeply into the lungs and can enter the bloodstream, potentially reaching the placenta which is the organ that supports fetal growth.
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The analysis found that the second trimester, particularly around the 21st week of pregnancy, was the most sensitive period.
During this time, the placenta grows rapidly and may be especially vulnerable to damage from pollution.
The link was most pronounced in the western United States, where wildfires and the resulting smoke are most frequent and intense.
Health guidance and next steps
Co-author Dr. Catherine Karr emphasized that public health guidance should reflect these findings.
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Experts suggest practical steps to reduce exposure during smoke events, such as staying indoors, using air filtration systems, and wearing protective masks when air quality declines.
As climate change drives more frequent and severe wildfires, researchers stress that understanding their effects on maternal and infant health has never been more urgent.
Sources: Medicalxpress, and The Lancet Planetary Health.
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