Birthing people with de novo postpartum hypertensive disorders continue to be among the populations at highest risk for severe maternal morbidity. Randomized controlled trials demonstrate a benefit of oral loop diuretics in decreasing postpartum hypertensive morbidity in patients with an antenatal diagnosis of preeclampsia. It is not known whether this same therapy benefits patients at risk for new-onset postpartum hypertension.

This study aimed to evaluate whether oral furosemide can reduce the risk for de novo postpartum hypertension among high-risk birthing people by reducing postdelivery blood pressure.

From October 2021 to April 2022, we conducted a randomized triple-masked placebo-controlled clinical trial of individuals at high risk for de novo postpartum hypertension at a single university-based tertiary care medical center. A total of 82 postpartum patients with no antenatal diagnosis of chronic hypertension or a hypertensive disorder of pregnancy who were at high risk for the development of de novo postpartum hypertension based on a prespecified risk factor algorithm were enrolled after childbirth. The participants were randomly assigned in a 1:1 ratio to a 5-day course of 20-mg oral furosemide daily or identical-appearing placebo starting within 8 hours of delivery. Participants were followed for 6 weeks postpartum using Bluetooth-enabled remote blood pressure monitoring and electronic surveys. The primary outcome was mean arterial pressure averaged over the 24 hours before discharge or the 24 hours before antihypertensive therapy initiation. The study was powered to detect a 5 mm Hg difference in average mean arterial pressure (standard deviation, 6.4 mm Hg) with 90% power at an alpha of 0.05, requiring a sample size of 41 per group. Secondary outcomes included the rate of de novo postpartum hypertension, readmission data, other measures of hypertensive and maternal morbidity, breastfeeding data, and drug-related neonatal outcomes.

The primary outcome was assessed in 80 of the 82 participants. Baseline characteristics were similar between the groups. There was no significant difference in average mean arterial pressure in the 24 hours before discharge (or antihypertensive initiation) in the furosemide group (88.9±7.4 mm Hg) compared with the placebo group (86.8±7.1 mm Hg; absolute difference, 2.1 mm Hg; 95% confidence interval, −1.2 to 5.3). Of the 79 participants for whom secondary outcomes were assessed, 10% (n=8) developed de novo postpartum hypertension and 9% (n=7) were initiated on antihypertensive therapy. Rates were not significantly different between the groups (P=.71 and P>.99, respectively).

De novo postpartum hypertension is a common phenomenon among at-risk patients, warranting close monitoring for severe hypertension and other maternal morbidity. There is insufficient evidence to suggest that furosemide reduces average mean arterial pressure in the 24 hours before discharge from the delivery hospitalization (or antihypertensive medication initiation) compared with placebo.

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