Low-Dose Aspirin Prophylaxis for Preeclampsia and the Risk of Postpartum Hypertensive Outcomes: A Propensity Score Analysis

Objective: The U.S. Preventive Services Task Force (USPSTF) recommends low-dose aspirin (LDA, 81 mg/day) after 12 weeks of pregnancy to reduce preeclampsia risk. While its effectiveness for prevention is well-established, less is known about the effects on postpartum hypertensive outcomes. This study aimed to examine whether LDA prescription in pregnancy (≤36 weeks' gestation) is associated with postpartum hypertensive outcomes through 6 weeks postpartum. Study Design: = 212). Primary outcomes included antihypertensive use during hospitalization, antihypertensive prescription at discharge, and severe-range postpartum hypertension. Risk ratios (RRs) were estimated using log-binomial regression. Joint effects of LDA and preeclampsia were assessed using LDA -/PreE- as reference. Results: In the primary matched cohort, compared with LDA- patients, LDA+ patients had higher rates of antihypertensive use during hospitalization (RR: 1.54, 95% confidence interval [CI]: 1.12-2.12), discharge prescription (RR: 1.42, 95% CI: 0.95-2.12), and severe-range hypertension (RR: 1.48, 95% CI: 1.06-2.06). Associations did not persist in the high-risk matched cohort. In joint effects analyses, preeclampsia was associated with postpartum hypertensive outcomes regardless of LDA. Compared with LDA -/PreE - , the LDA +/PreE+ group had elevated risks; point estimates were highest among LDA -/PreE+ patients. Conclusion: Associations between LDA and postpartum hypertensive outcomes may vary by baseline risk. Among high-risk patients, LDA was not associated with increased postpartum risk and may attenuate severity for those developing preeclampsia. Further study is needed to clarify LDA's role in reducing postpartum cardiovascular risk. Key Points: · LDA showed no overall reduction in postpartum hypertensive outcomes.. · In high-risk patients, LDA may lessen postpartum hypertensive complications.. · Among patients with preeclampsia, LDA use was linked to lower postpartum risks.. · Results highlight the need to study LDA in postpartum cardiovascular health..