Universal aspirin dispensation at the first prenatal visit could reduce the rate of preeclampsia with severe features by 29% in a high-risk population, according to findings from a large cohort study presented as a late-breaking abstract at the Society for Maternal-Fetal Medicine 2026 Pregnancy Meeting.
In the study, researchers compared two cohorts of 18,457 patients each: those who delivered prior to and following the implementation of direct aspirin dispensation at a Dallas public hospital. Beginning August 3, 2022, all patients presenting for prenatal care at 16 weeks' gestation or earlier received 162 mg of aspirin daily. Previously, aspirin wasn't recommended regardless of risk factors.
The rate of preeclampsia with severe features (SPE) dropped from 7% in the pre-implementation epoch to 5% in the aspirin epoch. Time to SPE diagnosis was also significantly longer in the group of patients who received aspirin.
Subgroup Findings
The protective effects extended across patients with and without chronic hypertension. Those with chronic hypertension who received aspirin had 0.72 times the risk of developing SPE compared with the pre-implementation cohort, whereas the patients without chronic hypertension had 0.63 times the risk.
Gestational hypertension rates also declined, from 21% to 19% of deliveries. Notably, the rate of preterm delivery prior to 37 weeks was reduced from 10% to 9%; however, delivery prior to 34 weeks remained unchanged at just over 3%.
Safety Outcomes
Contrary to theoretical concerns regarding aspirin and bleeding, postpartum hemorrhage—defined as estimated blood loss of at least 1,000 mL—decreased from 9.5% to 8.9% with aspirin administration. Placental abruption rates remained stable at less than 1% in both cohorts. Neonatal outcomes, including grade 3 or 4 intraventricular hemorrhage and gastroschisis, showed no statistically significant differences between the epochs.
Study Design and Limitations
The researchers included all deliveries at the hospital between April 2020 and July 2025 but excluded patients whose first prenatal visit occurred at 17 weeks' gestation or later as well as all deliveries during a 6-month washout period. SPE was clinically defined as preeclampsia requiring magnesium sulfate administration for severe hypertension or laboratory abnormalities.
Pharmacy data confirmed that 80.4% (n = 14,754) of the eligible patients—those with a prenatal visit at 16 weeks or earlier—received aspirin, with a median of 180 tablets dispensed per patient. The study population was predominantly Hispanic (81% and 84% in the pre-implementation and aspirin epochs, respectively), reflecting the demographics of the safety-net hospital system.
As an observational cohort study, the findings cannot establish causation. The researchers acknowledged that the results may not generalize to other patient populations with different risk profiles.
"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 study author Elaine L. Duryea, MD, Associate Professor in the Department of Obstetrics and Gynecology at the University of Texas Southwestern Medical Center and Chief of Obstetrics at Parkland Health in a companion press release. "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," she concluded.
The authors reported no conflicts of interest.
Source: Pregnancy
