New study: Routine aspirin therapy prevents severe preeclampsia in at-risk populations

Prescribing daily aspirin at the first prenatal visit to all pregnant patients was associated with an overall reduction in the development of severe preeclampsia, according to new research presented today at the Society for Maternal-Fetal Medicine (SMFM) 2026 Pregnancy Meeting™.  

Preeclampsia is a serious pregnancy complication that includes persistently high blood pressure and signs of organ damage such as protein in the urine or liver abnormalities. SPE, or preeclampsia with severe features, is a life-threatening pregnancy complication with dangerously high blood pressure and signs of damage to vital organs (liver, kidneys, or brain). Preeclampsia is one of the leading causes of maternal morbidity and mortality worldwide. Hypertensive disorders accounted for 7.7% of all pregnancy-related deaths in the U.S. in 2024, according to the U.S. Centers for Disease Control and Prevention.

Identification of preeclampsia involves blood pressure and symptom monitoring. Although low-dose aspirin therapy has been shown to help prevent preeclampsia among high-risk patients when started between 12 and 28 weeks of pregnancy, it remains underutilized and thus recent guidelines recommend consideration of universal aspirin use in high-risk pregnant populations.

To understand the effect of universal aspirin therapy in reducing SPE among a pregnant population with a high rate of preeclampsia, researchers provided 162 mg of daily aspirin to all patients at their first prenatal visit at or before 16-weeks' gestation beginning in August 2022. Importantly, the aspirin was directly dispensed to patients in prenatal clinics to overcome common barriers to medication usage. The researchers compared the outcomes of 18,457 patients who gave birth at Parkland Hospital in Dallas, TX, between 2023 and 2025, after the universal aspirin therapy practice change, to a similar number of patients before the use of aspirin.

The researchers found that pregnant patients who were given daily aspirin had a 29% lower rate of developing SPE compared with the group who did not receive aspirin. They also found that the patients given aspirin who developed SPE did so later in pregnancy compared to the control group. Patients with preexisting chronic hypertension before pregnancy who were given aspirin were also less likely to develop SPE. The study found no increase in maternal hemorrhage or placental abruption with aspirin therapy.

“Implementation of directly-dispensed aspirin in this high-risk pregnant population appeared to delay the onset, and for some patients completely prevent the development of preeclampsia with severe features,” said lead researcher Elaine L. Duryea, MD, Associate Professor in the Department of Obstetrics and Gynecology at the University of Texas Southwestern Medical Center in Dallas, and Chief of Obstetrics at Parkland Health. “While we cannot be sure that similar effects will be observed in other patient populations, there was no evidence of harm caused by aspirin administration.”    

Reference:

New study: Routine aspirin therapy prevents severe preeclampsia in at-risk populations, Society for Maternal-Fetal Medicine, Meeting: 2026 Pregnancy Meeting™