Aspirin prescription at first prenatal visit helps prevent pre-eclampsia

Prescribing daily aspirin at the first prenatal visit may result in the prevention of severe pre-eclampsia in women with or without chronic hypertension, reports a study presented at SMFM 2026.

“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 pre-eclampsia with severe features,” said lead researcher Dr Elaine L. Duryea, associate professor in the Department of Obstetrics and Gynecology at the University of Texas Southwestern Medical Center in Dallas, Texas, US.

“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 added.[https://www.smfm.org/news/new-studyroutine-aspirin-therapypreventsseverepreeclampsiainat-risk-populations]

Duryea and her team performed this inception cohort study in all deliveries at a public hospital between April 2020 and July 2025. Direct dispensation of aspirin 162 mg daily was initiated in patients presenting for prenatal care ≤16 weeks gestation on 3 August 2022. Aspirin was not previously recommended regardless of the presence of risk factors.

Patients who had their first prenatal visit ≥17 weeks gestation and all deliveries during the washout period of 3 August 2022 to 3 February 2023 were excluded from the analysis.

Duryea and colleagues used generalized estimating equations with a logit link to compare the rate of pre-eclampsia with severe features between the epochs. They also assessed time to diagnosis of severe pre-eclampsia using Kaplan-Meier plots with an associated log rank test.

Pre-eclampsia with severe features referred to “a clinical diagnosis with administration of magnesium sulfate for severe hypertension or lab abnormalities,” according to the researchers, who compared the outcomes in 18,457 patients after the implementation of the universal aspirin therapy practice to a similar number of patients prior to the use of aspirin.

The rate of severe pre-eclampsia was significantly lower among patients in the aspirin epoch than those before the implementation of universal aspirin therapy (5.19 percent vs 7.12 percent; odds ratio [OR], 0.71, 95 percent confidence interval [CI], 0.66‒0.78; p<0.001). The time to a diagnosis of pre-eclampsia was also longer in the aspirin epoch (p<0.001). [SMFM 2026, abstract LB02]

Furthermore, both patients with and without chronic hypertension appeared to benefit from the universal aspirin therapy, as shown by the significant reduction in the likelihood of developing severe pre-eclampsia (with chronic hypertension: OR, 0.72, 95 percent CI, 0.60‒0.87; without chronic hypertension: OR, 0.63, 95 percent CI, 0.57‒0.70).

Notably, there was no change in the rate of neonatal intraventricular haemorrhage and gastroschisis, as well as in the frequency of placental abruption. A decrease was also observed in the rate of postpartum haemorrhage, defined as blood loss >1,000 mL, with aspirin use (9.5 percent vs 8.9 percent; p=0.03).

Based on pharmacy data for the aspirin epoch, a total of 14,754 (80.4 percent) patients with a prenatal visit ≤16 weeks were prescribed aspirin, with a median of 180 tablets dispensed per patient.

“[U]niversal aspirin dispensation at the first prenatal visit was associated with a population-level reduction in the development of [severe pre-eclampsia] in patients with and without chronic hypertension, without an increase in haemorrhage or abruption,” Duryea said.