Study explores pregnancy risks from heat and wildfire smoke

Wildfire smoke and extreme heat – increasingly the new norm – each have their own harmful effects on pregnant people and babies, including preterm birth and low birthweight. Now University of Maryland School of Public Health (UMD SPH) researchers will lead a $2.5 million grant from the National Institutes of Health (NIH) to examine how the combined experience of these hazards affects maternal health in the United States. 

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."

Dr. Jennifer Stowell, study's principal investigator, environmental epidemiologist and assistant professor in SPH's Department of Global, Environmental and Occupational Health

"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." 

Drawing data from 6.5 million births over two decades, Stowell and her colleagues will measure exposure to extreme heat, wildfire smoke particles (PM2.5) and other pollutants against the incidence of serious pregnancy complications such as hypertension and gestational diabetes. Hypertensive disorders of pregnancy (HDP) and gestational diabetes mellitus (GDM) 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 and demands 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 regular air pollution are linked to pregnancy complications and loss, cardiovascular stress and postpartum mental health, little is known about the impacts of wildfire smoke on pregnancy. 

"We will look at the effect of exposure to all of these things at once, because they are increasingly happening all at once. 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," said Stowell.