Misoprostol administered sublingually at a dose of 12.5 μg versus vaginally at a dose of 25 μg for the induction of full-term labor: a randomized controlled trial protocol

Efficacy and safety of oral and sublingual versus vaginal misoprostol for induction of labour: a systematic review and meta-analysis

Objective

Misoprostol is a synthetic PGE1 analogue that is used for induction of labour. Current guidelines support the use of doses that do not exceed 25 mcg in order to limit maternal and neonatal adverse outcomes. The present meta-analysis investigates the efficacy and safety of oral compared to vaginally inserted misoprostol in terms of induction of labor and adverse peripartum outcomes.

Methods

We searched Medline, Scopus, the Cochrane Central Register of Controlled Trials CENTRAL, Google Scholar, and Clinicaltrials.gov databases from inception till April 2022. Randomized controlled trials that assessed the efficacy of oral misoprostol (per os or sublingual) compared to vaginally inserted misoprostol. Effect sizes were calculated in R. Sensitivity analysis was performed to evaluate the possibility of small study effects, p-hacking. Meta-regression and subgroup analysis according to the dose of misoprostol was also investigated. The methodological quality of the included studies was assessed by two independent reviewers using the risk of bias 2 tool. Quality of evidence for primary outcomes was evaluated under the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework, ranging from very low to high.

Results

Overall, 57 studies were included that involved 10,975 parturient. Their risk of bias ranged between low-moderate. There were no differences among the routes of intake in terms of successful vaginal delivery within 24 h (RR 0.90, 95% CI 0.80) and cesarean section rates (RR 0.92, 95% CI 0.82, 1.04). Sublingual misoprostol was superior compared to vaginal misoprostol in reducing the interval from induction to delivery (MD – 1.11 h, 95% CI – 2.06, – 0.17). On the other hand, per os misoprostol was inferior compared to vaginal misoprostol in terms of this outcome (MD 3.45 h, 95% CI 1.85, 5.06). Maternal and neonatal morbidity was not affected by the route or dose of misoprostol.

Conclusion

The findings of our study suggest that oral misoprostol intake is equally safe to vaginal misoprostol in terms of inducing labor at term. Sublingual intake seems to outperform the per os and vaginal routes without increasing the accompanying morbidity. Increasing the dose of misoprostol does not seem to increase its efficacy.

Clinical trial registration

Open Science Framework (https://doi.org/10.17605/OSF.IO/V9JHF).

Factors associated with delayed onset of active labor following vaginal misoprostol administration among women at Mbarara Regional Referral Hospital, Uganda

OBJECTIVE

To determine the factors associated with delayed onset of active labor following labor induction with vaginal misoprostol.

METHODS

We conducted a prospective cohort study over 6 months at a tertiary hospital in Uganda. We enrolled mothers with pregnancies of at least 28 weeks, who were undergoing labor induction with 50 µg of vaginal misoprostol, administered every 6 hours with a maximum of four doses, and followed them up until onset of active labor. Labor onset was considered delayed if it occurred later than 12 hours after the first dose. Bivariate and multivariate analysis was performed to determine factors associated with delayed onset of active labor.

RESULTS

Of the 88 mothers enrolled, 22.7% (n=20) had delayed onset of active labor. Nulliparity (adjusted relative risk [aRR] 2.34, 95% confidence interval [CI] 1.17-4.68) and gestational age less than 37 weeks (aRR 3.79, 95% CI 1.40-10.23) were associated with delayed onset of active labor following vaginal misoprostol administration whereas higher body mass index (aRR 0.38, 95% CI 0.18-0.79) decreased the risk.

CONCLUSION

Delayed onset of active labor following labor induction remains an important obstetric care challenge. Mothers undergoing labor induction should have their body mass index documented, and nulliparous women and mothers at less than 37 weeks of gestation should have their labor monitored for a longer duration following labor induction.