- September 21, 2026
- By Fid Thompson
As unusually hot weather stokes a bad season for U.S. wildfires, a new $2.5 million award from National Institutes of Health is funding a University of Maryland study on how the blazes and atmospheric heat impact pregnancies.
Both environmental factors have been previously shown to harm maternal health, and the study by School of Public Health (SPH) researchers will be the largest yet to gauge their combined toll.
“We will look at the effect of exposure to all of these things at once, because they are increasingly happening all at once,” said the study’s principal investigator, Jennifer Stowell, an environmental epidemiologist and assistant professor in SPH’s Department of Global, Environmental and Occupational Health. “And combined exposure could mean greater damage to the heart and respiratory system, which uniquely affects pregnant people and their babies. We hope this study will help us better understand these effects, so we can better protect millions of women exposed to wildfire smoke and heat each year.”
Drawing data from 6.5 million births over two decades, Stowell and her colleagues will measure exposure to extreme heat, tiny wildfire smoke particles and other pollutants against the incidence of serious pregnancy complications such as hypertension and gestational diabetes. Hypertensive disorders of pregnancy and gestational diabetes mellitus affect approximately 10% and 8%, respectively, of pregnancies in the United States, disproportionately impacting marginalized communities.
Pregnant people are especially vulnerable to both extreme heat and wildfire smoke because pregnancy reduces the body's capacity to regulate heat while demanding more from the heart and respiratory system. Ingesting tiny particles from wildfire smoke and experiencing elevated heat days have each separately been linked to smaller average size during gestation, in addition to preterm birth and low birthweight.
While extreme heat and more widely studied forms of air pollution are tied to pregnancy complications and loss, cardiovascular stress and postpartum mental health, little is known about the impacts of wildfire smoke on pregnancy.
“We aim to identify which pollutant combinations and what time periods during pregnancy matter most and to map out how risk looks across different areas,” Stowell said. “What we learn from this research will provide crucial information for clinical guidance, improved services in under-resourced perinatal care regions, such as rural areas, and better early-warning systems for high-risk groups like low-income and minority populations.”