Findings from a first-of-its-kind study led by University of California, Irvine suggest pregnant women exposed to a higher level of air pollution may have a higher risk of spontaneous premature rupture of membranes (SPROM), a critical obstetrical problem that can significantly increase maternal and fetal mortality and morbidity.
To uncover the danger of air pollution exposure to pregnant women, co-corresponding author Jun Wu, PhD, a professor of environmental & occupational health at the UCI Program in Public Health, collaborated with researchers to publish a study in Environmental International.
With evidence linking certain maternal characteristics to the premature rupture of membranes (PROM), such as low body mass index and cigarette smoking, associations with maternal exposure to air pollutants remain limited and inconclusive. Wu and team carried out a retrospective cohort study of about 340,000 mothers who were members of Kaiser Permanente Southern California and estimated their exposure to air pollution based on residential addresses. Findings showed that maternal exposure to nitrogen dioxide, ozone, and chemicals on particulate matter < 2.5 µm (PM2.5) such as sulfate, nitrate, and organic matter were consistently associated with increased risks of SPROM, and the critical exposure windows varied by each air pollutant: early pregnancy for ozone, mid to late pregnancy for PM2.5, and early and late pregnancy for nitrogen dioxide.
Understanding susceptible windows for air pollution can help reveal underlying mechanisms that trigger SPROM and how to target against the specific air pollutants that cause the most damage.”
– Jun Wu, PhD
PROM is the breaking open of the amniotic sac before labor begins. This critical event can increase risks of intra-amniotic infections, placental abruption, cord prolapse, sepsis, and death for mothers as well as morbidity for newborns, such as respiratory distress syndrome. These considerable risks of poor maternal and fetal outcomes are driving researchers to uncover the potential risk factors underlying this event.
“Understanding susceptible windows for air pollution can help reveal underlying mechanisms that trigger SPROM and how to target against the specific air pollutants that cause the most damage,” says Wu. “Ozone appears to be more harmful among the air pollutants that we studied so it warrants further targeted research in different locations to explore this association.”
“SPROM is a leading cause of preterm birth and is associated with serious pregnancy complications. Understanding the associations between exposure to air pollution and SPROM can help to reduce the risk of SPROM and preterm birth,” says Anqi Jiao, the first author of the paper and a PhD student in the Department of Environmental and Occupational Health at the UCI Program in Public Health. “This is the first study to report maternal exposure to PM2.5 components as a risk factor for SPROM.”
Additional authors include Darios Getahun, PhD, Chantal Avila, MA, Vicki Chiu, MS, Jeff Slezak, MS, and David A. Sacks, MD, all from the Kaiser Permanente Southern California Department of Research & Evaluation; John Molitor, PhD, from Oregon State University; Tarik Benmarhnia, PhD, from University of California, San Diego; Jiu-Chiuan Chen, MD, ScD, from University of
Southern California and Yi Sun, PhD, from University of California, Irvine Program in Public Health. Dr. Getahun is also affiliated with the Kaiser Permanente Bernard J. Tyson School of Medicine.
