Comparison of Labour Induction Outcomes with Sublingual versus Oral Misoprostol at Term: A Retrospective Cohort Study

Abstract

Background: Misoprostol can be administered through several routes for cervical ripening and labour induction. Route-related differences in absorption may influence the amount of drug required and the time from induction to birth, while maternal and neonatal safety must remain central.

Objectives: To compare induction efficiency, mode of delivery, maternal and intrapartum fetal safety outcomes, and early neonatal outcomes among term pregnancies managed with sublingual or oral misoprostol.

Methods: This retrospective cohort study included 50 term pregnancy records, with 25 women in the sublingual group and 25 in the oral group. Each administration contained 50 µg misoprostol. The principal outcome was the induction-to-delivery interval. Secondary outcomes included number and cumulative dose of misoprostol, oxytocin augmentation, delivery mode, uterine hyperstimulation, tachysystole, fetal distress or non-reassuring fetal status leading to caesarean delivery, postpartum haemorrhage, birth weight, Apgar scores, and neonatal intensive care unit admission. Continuous variables were compared using Welch’s t-test or the Mann-Whitney U test, while categorical variables were assessed using the chi-square test or Fisher’s exact test.

Results: Baseline age, parity, gestational age, Bishop Score, and indications for induction were comparable between groups. The sublingual group required fewer doses (median 2 versus 3; p=0.032) and a lower cumulative dose (median 100 versus 150 µg; p=0.032). Mean induction-to-delivery interval was 13.85±3.26 hours with sublingual administration and 20.14±3.32 hours with oral administration (mean difference 6.29 hours; 95% CI 4.42–8.16; p<0.001). Caesarean delivery occurred in 5 (20%) and 6 (24%) women, respectively. Fetal distress or non-reassuring fetal status leading to caesarean delivery occurred in 2 (8%) women in each group. Hyperstimulation, tachysystole, postpartum haemorrhage, birth weight, Apgar scores, and neonatal intensive care unit admission did not differ significantly.

Conclusion: In this cohort, sublingual misoprostol was associated with a shorter induction-to-delivery interval and lower drug exposure than the oral route. Fetal distress or non-reassuring fetal status was recorded equally in both groups, and the study did not demonstrate a fetal safety advantage for either route. Current guideline-supported practice favours low-dose oral misoprostol were incorporated into institutional protocols; the present findings should not be interpreted as support for routine 50 µg sublingual administration.