Objective: The objective is to report the effect of universal aspirin dispensation in a population where the majority of patients are at moderate or high risk of preeclampsia.
Study Design: This inception cohort study includes all deliveries at a public hospital between April 2020 to July 2025. On August 3, 2022 direct dispensation of aspirin 162mg daily to all patients presenting for prenatal care ≤16 weeks gestation began. Prior, aspirin was not recommended regardless of risk factors. Preeclampsia with severe features (SPE) was a clinical diagnosis with administration of magnesium sulfate for severe hypertension or lab abnormalities. Analysis exclusion criteria included first prenatal visit ≥17 weeks gestation and all deliveries during the washout period of 8/3/2022 to 2/3/2023. Generalized estimating equations with a logit link were used to compare SPE rate between the epochs. Kaplan Meier plots with an associated log rank test were performed to examine time to diagnosis of SPE.
Results: Two cohorts of 18,457 patients, before and after aspirin implementation, were compared. Patients in the aspirin epoch had a 29% lower rate of SPE (7.12% vs. 5.19%, OR 0.71(0.66–0.78), p < 0.001) (Table). Additionally, the time to SPE diagnosis was longer in the aspirin epoch, p < 0.001 (Figure). Patients with chronic hypertension were less likely to develop SPE (OR 0.72 (0.60–0.87)), as were those without chronic hypertension (OR 0.63 (0.57–0.70)) in the aspirin epochs. The rate of neonatal IVH and gastroschisis did not change, nor did frequency of placental abruption. The rate of postpartum hemorrhage defined as blood loss >1,000mL decreased with aspirin (9.5% vs. 8.9%, p = 0.03). Pharmacy data for the aspirin epoch confirmed 14,754 (80.4%) patients with a prenatal visit ≤16 weeks received aspirin, with a median of 180 tablets dispensed per patient.
Conclusion: Conclusions: Implementation of universal aspirin dispensation at the first prenatal visit was associated with a population-level reduction in the development of SPE in patients with and without chronic hypertension, without an increase in hemorrhage or abruption.