Universal aspirin prophylaxis is associated with 29% reduction in severe preeclampsia

Universal aspirin dispensation at the first prenatal visit was associated with a 29% reduction in preeclampsia with severe features across an entire obstetric population, with benefit observed in patients both with and without chronic hypertension, according to findings from a large inception cohort study conducted at a public urban hospital.¹

The study compared outcomes among 18,457 patients before and after the implementation of universal aspirin 162 mg daily in August 2022 at a large urban county hospital. Prior to implementation, aspirin had not been routinely recommended regardless of risk factors. Following implementation, 80.4% of eligible patients—those with a prenatal visit at or before 16 weeks—received aspirin, with a median of 180 tablets dispensed per patient.

"We implemented universal aspirin to all patients that presented for prenatal care by 16 weeks gestation," said lead investigator Elaine Duryea, MD, chief of obstetrics at Parkland Health and an associate professor of maternal-fetal medicine at the University of Texas Southwestern Medical Center in Dallas. "Prior to this, we had not routinely recommended aspirin to our patients, even those of moderate or high risk for preeclampsia."

Patients in the aspirin epoch had a significantly lower rate of preeclampsia with severe features (5.19% vs. 7.12%; OR 0.71; 95% CI, 0.66–0.78; P < .001), with time to diagnosis also significantly delayed. The benefit held across subgroups: patients with chronic hypertension (OR 0.72; 95% CI, 0.60–0.87) and those without (OR 0.63; 95% CI, 0.57–0.70) both demonstrated significant reductions.

"The finding that really stood out to me the most was how the improvement in outcomes was really across all populations," Duryea said. "It demonstrated effect in women with hypertension and in those who had no risk factors."

The choice of 162 mg daily—rather than the 81-mg dose commonly used in the United States—was deliberate. Duryea noted that a substantial proportion of pregnant patients, particularly in later pregnancy, do not achieve a full aspirin response at 81 mg, and that the largest RCT demonstrating benefit for preeclampsia prevention tested 150 mg daily.

"Those two pieces of evidence are really what guided our decision," she said, adding that the dosing question represents "an important talking point going forward looking at our national guidelines."

Concerns about bleeding risk were not borne out in the data. Rates of postpartum hemorrhage, neonatal intraventricular hemorrhage, gastroschisis, and placental abruption did not increase; the rate of postpartum hemorrhage defined as blood loss greater than 1000 mL modestly decreased in the aspirin epoch (9.5% vs. 8.9%; P = .03).

"The real number one takeaway was that aspirin demonstrates safety," Duryea said. "We demonstrated safety with aspirin in pregnancy."

On generalizability, Duryea acknowledged that the institution's predominantly moderate- to high-risk population aligns with current American College of Obstetrics & Gynecology and US Preventive Services Task Force guidance. Yet the observed benefit even among lower-risk patients raises a broader question.

"It does beg the question, is risk stratification really the direction we want to go, or is a more wide application possibly going to yield more benefit?" she said. For clinicians practicing in lower-risk settings, she framed the findings as informing rather than mandating a change in counseling.

"If a patient who is low risk for developing preeclampsia desires to take aspirin in pregnancy, that would be a reasonable choice for them."

Reference:

1. Duryea EL, Ambia AM, Pruszynski JE, et al. Universal aspirin administration for prevention of preeclampsia. Presented at: Society for Maternal-Fetal Medicine 2026 Pregnancy Meeting. February 8-13, 2026. Las Vegas, Nevada. Abstract LBA02