• Posted February 13, 2023

Wildfire Smoke May Send Pregnant Women Into Premature Labor

Exposure to wildfire smoke can increase the risk of premature birth, new research suggests.

For the study, the researchers reviewed birth certificates and hospital delivery data for more than 2.5 million pregnant women in California from 2007 to 2012, and used satellite images and ZIP codes to compare daily estimates of wildfire smoke intensity.

The study found that from the four weeks prior to conception and through the first 20 weeks of pregnancy, 86% of the women were exposed to at least one day of wildfire smoke. They had an average exposure of 7.5 days.

Wildfire smoke was significantly associated with spontaneous preterm birth, the investigators found. Each additional day of smoke exposure slightly increased the odds of delivering prematurely.

"Wildfires lead to acute and abrupt changes in air quality,"said lead study author Dr. Anne Waldrop, a maternal-fetal medicine subspecialist fellow at Stanford University in Palo Alto, Calif.

"And some emerging evidence suggests that wildfire smoke could be worse for your health than other types of pollutants. So, even as we work to decrease other forms of air pollution, with wildfires becoming more frequent, more intense, and happening on a much larger scale, exposure to wildfire smoke is a serious public health problem, especially for vulnerable populations like pregnant people,"Waldrop said in a news release from the Society for Maternal-Fetal Medicine.

Wildfire smoke contains extremely fine particles that can enter deep into the lungs. These may worsen medical conditions such as asthma and heart disease.

Past research has found that poor air quality can lead to a number of adverse outcomes, including preterm birth, one of the leading causes of infant death worldwide.

Findings from the new study were presented Saturday at a meeting of the Society for Maternal-Fetal Medicine in San Francisco and online.

They were also recently published in the American Journal of Obstetrics & Gynecology.

More information

The U.S. Environmental Protection Agency has more on wildfire smoke and health concerns.

SOURCE: Society for Maternal-Fetal Medicine, news release, Feb. 11, 2023