BIDMC-Led Study Finds Low-Dose Aspirin May Reduce Risk of Preterm Births in Extreme Heat Climate
New Findings Highlight Role of Aspirin in Climate-Linked Pregnancy Health
BOSTON — Rising temperatures are contributing to worse health outcomes for mothers and newborns, with mounting evidence linking extreme heat to preterm (often called premature) birth and other complications. Preterm birth is already a leading cause of infant illness and death worldwide, with an estimated 12 to 15 million babies born too early each year, meaning even modest increases in heat-related risk could have substantial global consequences.
Research led by physician-scientists at Beth Israel Deaconess Medical Center (BIDMC) points to a practical way to help reduce that risk. In a secondary analysis published May 6 in JAMA Network Open, the team found that humid heat exposure during pregnancy was associated with higher odds of preterm birth, but not among those who took low-dose aspirin starting early in pregnancy.
“Extreme heat events are intensifying in frequency and severity, with the 10 warmest years on record all occurring in the past decade,” said corresponding and senior author Blair J. Wylie, MD, MPH, chair of obstetrics and gynecology at BIDMC. “Scalable interventions are urgently needed to mitigate the adverse effects of heat on pregnancy and newborn health.”
The analysis drew on data from a large, NIH-funded randomized clinical trial known as the Global Network for Women’s and Children’s Health Research ASPIRIN trial. More than 11,500 first-time pregnant people across seven countries in Africa, South Asia, and Latin America were enrolled and randomly assigned to receive either daily low-dose aspirin or a placebo beginning early in pregnancy to assess whether aspirin could reduce the risk of preterm birth and other adverse outcomes.
Wylie and colleagues linked each participant’s location to high-resolution climate data to estimate heat exposure, using a measure that combines temperature, humidity, sunlight, and wind to reflect how hot it actually feels. They then examined how this humid heat exposure was associated with preterm birth, defined as delivery before 37 weeks.
Among participants who did not take low-dose aspirin, each 1°C increase in average daily humid heat during pregnancy was associated with a 5 percent increase in the odds of preterm birth — while this is a modest effect, on a population level this translates to many more preterm births. This increased risk was not observed among those who took low-dose aspirin early in pregnancy.
Low-dose aspirin is already routinely used in some pregnancies to reduce the risk of conditions such as preeclampsia, and the findings suggest it could offer a practical, low-cost way to reduce heat-related risk. At the same time, the study underscores how rising temperatures are reshaping risks for pregnant people and their babies. The 10 warmest years on record have all occurred in the past decade, and extreme heat has been linked to preterm birth, low birth weight, and stillbirth.
The findings come with important caveats. The study also observed that heat exposure was associated with perinatal mortality among participants who did take aspirin, particularly in areas where malaria is endemic, highlighting the need for further studies.
“The increasing global prevalence of heat stress warrants testing the effects of aspirin more broadly among pregnant people as well as its safety with respect to perinatal mortality,” Wylie said.
Please see the paper for a complete list of co-authors.
The initial ASPIRIN trial was funded by grants from the US National Institute of Child Health and Human Development to the Global Network for Women’s and Children’s Health Research. This analysis was funded by in-kind support to The Collaborative for Women’s Environmental Health at Columbia University.
Dr Wylie reported grants from NICHD, employment at Columbia University (during the initial portion of this work; Columbia received philanthropic support that was directed for use related to environmental issues, and that support was used to support obtaining the climate data and supporting the analysis), and serving on the Executive Committee of the Board of the Society for Maternal-Fetal Medicine and receiving support for travel to meetings.
About Beth Israel Deaconess Medical Center
Beth Israel Deaconess Medical Center is a leading academic medical center, where extraordinary care is supported by high-quality education and research. BIDMC is a teaching affiliate of Harvard Medical School, and consistently ranks as a national leader among independent hospitals in National Institutes of Health funding. BIDMC is the official hospital of the Boston Red Sox.
Beth Israel Deaconess Medical Center is a part of Beth Israel Lahey Health, a healthcare system that brings together academic medical centers and teaching hospitals, community and specialty hospitals, more than 4,700 physicians and 39,000 employees in a shared mission to expand access to great care and advance the science and practice of medicine through groundbreaking research and education.
