Addition of vaginal isosorbide mononitrate for labor induction in pregnancies complicated by hypertensive diseases of pregnancy: a randomized controlled trial

BACKGROUND: Pregnancies complicated by hypertensive disease of pregnancy often require labor induction. Rates of cesarean delivery range from 15% to 60% in this population. Nitric oxide deficiency has been shown to underlay the pathophysiology of preeclampsia, and nitric oxide promotes cervical ripening. OBJECTIVE: We hypothesized that addition of vaginal isosorbide mononitrate for labor induction could decrease the rate of cesarean delivery in pregnancies with hypertensive disease of pregnancy. STUDY DESIGN: This study was a double-blind, placebo-controlled, randomized trial of patients with singleton pregnancy at >= 24 weeks' gestation undergoing labor induction for hypertensive diseases of pregnancy between November 2017 and February 2020. Participants were eligible if their Bishop score was <6 and if their cervical dilation was <= 2 cm. In addition, participants received up to 3 doses of 40 mg isosorbide mononitrate in addition to misoprostol for labor induction. Labor management was per healthcare provider preference. The primary outcome was rate of cesarean delivery. Secondary outcomes included the length of labor and frequency of intrapartum adverse events, including the use of intrapartum antihypertensive agents. RESULTS: 89 women were randomized to the isosorbide mononitrate group, and 87 women were randomized to the placebo group. Cesarean delivery rates were similar in both groups (32.6% vs 25.3%; relative risk, 1.29; 95% confidence interval, 0.81-2.06; P=.39). Maternal headache was increased in patients exposed to isosorbide mononitrate (42.7% vs 31%; relative risk, 1.52; 95% confidence interval, 1.04-2.23; P=.04). Clinical chorioamnionitis was increased in the placebo group (0% vs 8%; P=.02). Secondary outcomes were similar between groups. CONCLUSION: The addition of vaginal isosorbide mononitrate for labor induction in pregnancies complicated by hypertensive disease of pregnancy did not result in fewer cesarean deliveries.

Automated summary

A study on using isosorbide mononitrate for labor induction in pregnancies complicated by hypertensive disease did not decrease the rate of cesarean deliveries, showing no significant difference between the isosorbide mononitrate group and the placebo group.