On Jun. 3, 2025, a study by Emory University researchers, published in Environmental Science & Technology, found that exposure to the tiny particles in air pollution during pregnancy can disrupt maternal metabolisms, altering key biological pathways. These changes were associated with increased risk of various negative birth outcomes, including premature birth.

The study, which analyzed blood samples provided by 330 pregnant women from the Atlanta metropolitan area, is believed to be the first to investigate how exposure to ambient fine particulate matter (PM2.5) commonly found in air pollution affects the metabolism of pregnant women and contributes to increased risks of preterm and early term births.

Previous research has shown pregnant women and fetuses are more vulnerable than other populations to exposure to PM2.5—which is emitted from combustion sources such as vehicle exhaust, industrial processes, and wildfires—including increased likelihood of preterm births (less than 37 weeks of gestation), which is the leading cause of death globally among children under the age of five.

Preterm birth is also linked to complications such as cerebral palsy, respiratory distress syndrome, and long-term noncommunicable disease risks, while early term births (37-39 weeks of gestation) are also associated with increased neonatal morbidity and developmental challenges. Approximately 10% of the preterm births in the world are attributable to PM2.5 exposure.

This was the first study to uncover the specific pathways and molecules involved in energy and amino acid metabolism that may explain how exposure to PM2.5 contributes to preterm and early term births. Of the 330 women who participated in the Emory study, 66 (20%) delivered preterm babies and 54 (16.4%) delivered early term babies, both of which are significantly higher than the prevalence in the general U.S. population.