Is oral misoprostol more effective than vaginal dinoprostone for cervical ripening in women with preeclampsia or gestational hypertension: a retrospective cohort study

Abstract OBJECTIVE: To compare the effects of oral misoprostol and vaginal dinoprostone on cervical ripening and labor induction among patients with preeclampsia or gestational hypertension. METHODS: A total of 123 women with preeclampsia or gestational hypertension, who had indications for pregnancy termination and no contraindications for vaginal delivery at 37 weeks of gestation or beyond, with Bishop scores below 6, were included in this trial conducted at Hebei General Hospital in Shijiazhuang, Hebei, China, between October 2022 and May 2023. Participants were randomly assigned to receive either oral misoprostol or vaginal dinoprostone. In the oral misoprostol group (n=60), a dose of 25 to 50µg was administered every 2 or 4 hours. In the vaginal dinoprostone group (n=63), the 10mg dinoprostone vaginal insert was administered as per the drug protocol. The efficacy and safety of oral misoprostol were compared to those of vaginal dinoprostone for labor induction in women with preeclampsia or gestational hypertension. RESULTS: The duration of induction to cervical ripening was significantly longer in the oral misoprostol group compared to the vaginal dinoprostone group (32.77 hours vs 16.09 hours, p=0.007). Similarly, the delivery time was longer in the oral misoprostol group compared to the vaginal dinoprostone group (39.15 hours vs 11.57 hours, p=0.019). The time from cervical ripening to delivery was also longer in the oral misoprostol group compared to the vaginal dinoprostone group (10.85 hours vs 4.5 hours, p=0.004). Compared to vaginal dinoprostone, the use of oral misoprostol resulted in a higher need for additional induction methods such as oxytocin, mechanical devices, or amniotomy (43.33% vs 4.76%, p＜0.001). However, there was a lower incidence of hyperstimulation with oral misoprostol compared to vaginal dinoprostone (5% vs 28.57%, p=0.001, RR 0.26, 95% CI 0.08 to 0.74). There was no significant difference in the rate of cesarean delivery between the two groups. Nevertheless, it is worth noting that women who received oral misoprostol had a significantly lower likelihood of undergoing cesarean delivery due to non-reassuring fetal heart rate (20% vs 66.67%, p=0.04, RR 0.25, 95% CI 0.07 to 0.98) compared to those in the vaginal dinoprostone group. No cases of severe neonatal or maternal morbidity were reported, and there were no significant differences in other clinically relevant outcomes. CONCLUSIONS: In terms of induction and delivery time, oral misoprostol appears to be less effective than vaginal dinoprostone. While it results in a lower frequency of tachysystole and non-reassuring fetal heart rate (FHR) changes, the rates of cesarean delivery and maternal and fetal complications are similar between the two groups. Additionally, the oral misoprostol group requires additional methods to achieve vaginal delivery. Therefore, oral misoprostol does not demonstrate superiority in achieving vaginal delivery for patients with preeclampsia or gestational hypertension.