Misoprostol 50 μg Sublingually versus Vaginally for Labor Induction at Term: A Randomized Study

Comparison of the Efficacy and Safety of Sublingual Versus Oral Misoprostol for the Induction of Labor: A Randomized Open-Label Study

Introduction Misoprostol (prostaglandin E1 analog) is being used for the induction of labor by vaginal, oral, and sublingual routes. Oral misoprostol is the preferred route for induction of labor, but the use of sublingual misoprostol appears promising due to a faster onset of action. This study was done to compare the efficacy and safety of oral and sublingual misoprostol for induction of labor in term pregnancy. Materials and methods One hundred and sixty patients were randomly allocated to one of the two groups to receive 50 micrograms of oral and sublingual misoprostol four hourly for a maximum of six doses. Primigravida at 37-42 weeks of gestation with singleton pregnancy, cephalic presentation, Bishop score (<5), and reassuring fetal heart rate were included in the study. Misoprostol dose was withheld if the active phase of labor was reached or if the cervix was favorable for amniotomy (Bishop score greater than or equal to eight). The change in the Bishop score with misoprostol was studied along with adverse effects and neonatal outcomes. Results The mean number of 50 mcg misoprostol doses required was significantly less in the sublingual group (2.94±0.97 versus 2.13±0.92; p<0.0001). The rate of change of the mean Bishop score was faster in the sublingual group. After four hours of the first dose, the mean Bishop score changed to 3.52±2.14 versus 4.68±2.34 (p=0.001), and, similarly, after eight hours, it was 10.48±2.59 versus 11.39±2.06, and this difference was statistically significant (p=0.015). The mean induction delivery interval was significantly lower in the sublingual group. The need for labor augmentation, mode of delivery, and adverse effects were similar in both groups. The incidence of meconium-stained liquor and NICU admission was also similar in both groups. Conclusion Sublingmisoprostolstol has a short induction delivery interval and comparable side effects when compared to omisoprostolstol. Sublingmisoprostolstol is recommended for induction of labor at term.

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).

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

Background

Labor induction is defined as any procedure that stimulates uterine contractions before labor begins spontaneously. The vaginal and oral routes of administration of misoprostol are those most used for the induction of labor in routine practice, with the recommended dose being 25 μg. Nevertheless, the sublingual route may reduce the number of vaginal examinations required, increasing patient comfort and lowering the risk of maternal and fetal infection. Based on a previous systematic review, the objective of this study was to compare the frequency of tachysystole as the main outcome measure when misoprostol is administered sublingually at the dose of 12.5 μg versus vaginally at a dose of 25 μg to induce labor in a full-term pregnancy with a live fetus.

Methods

A randomized, placebo-controlled, triple-blind clinical trial was conducted at two maternity hospitals in northeastern Brazil. Two hundred patients with a full-term pregnancy, a live fetus, Bishop score ≤ 6 and an indication for induction of labor were included. Following randomization, one group received 12.5 μg misoprostol sublingually and a vaginal placebo, while the other group received a sublingual placebo and 25 μg misoprostol vaginally. The primary outcome was the frequency of tachysystole. Student’s t-test, the chi-square test of association and Fisher’s exact test were used, as appropriate. Risk ratios and their 95% confidence intervals were calculated.

Results

The frequency of tachysystole was lower in the group using 12.5 μg misoprostol sublingually compared to the group using 25 μg misoprostol vaginally (RR = 0.15; 95%CI: 0.02–0.97; p = 0.002). Failure to achieve vaginal delivery within 12 and 24 h was similar in both groups. Sublingual administration was preferred to vaginal administration by women in both groups; however, the difference was not statistically significant.

Conclusion

The effectiveness of labor induction with low-dose sublingual misoprostol was similar to that achieved with vaginal administration of the recommended dose; however, the rate of tachysystole was lower in the sublingual group, and this route of administration may prove a safe alternative.

Trial registration

Registration number: NCT01406392, ClinicalTrials.gov. Date of registration: August 1, 2011.

A comparison of vaginal versus buccal misoprostol for cervical ripening in women for labor induction at term (the IMPROVE trial): a triple-masked randomized controlled trial

BACKGROUND

Cervical ripening is commonly needed for labor induction. Finding an optimal route of misoprostol dosing for efficacy, safety, and patient satisfaction is important and not well studied for the buccal route.

OBJECTIVE

To compare the efficacy and safety of vaginal and buccal misoprostol for women undergoing labor induction at term.

STUDY DESIGN

The IMPROVE trial was an institutional review board-approved, triple-masked, placebo-controlled randomized noninferiority trial for women undergoing labor induction at term with a Bishop score ≤6. Enrolled women received 25 mcg (first dose), then 50 mcg (subsequent doses) of misoprostol by assigned route (vaginal or buccal) and a matching placebo tablet by the opposite route. The primary outcomes were time to delivery and the rate of cesarean delivery performed urgently for fetal nonreassurance. A sample size of 300 was planned to test the noninferiority hypothesis.

RESULTS

The trial enrolled 319 women, with 300 available for analysis, 152 in the vaginal misoprostol group and 148 in the buccal. Groups had similar baseline characteristics. We were unable to demonstrate noninferiority. The time to vaginal delivery was lower for the vaginal misoprostol group (median [95% confidence interval] in hours: vaginal: 20.1 [18.2, 22.8] vs buccal: 28.1 [24.1, 31.4], log-rank test P = .006, P_{noninferiority} = .663). The rate of cesarean deliveries for nonreassuring fetal status was 3.3% for the vaginal misoprostol group and 9.5% for the buccal misoprostol group (P = .033). The rate of vaginal delivery in <24 hours was higher in the vaginal group (58.6% vs 39.2%, P = .001).

CONCLUSION

We were unable to demonstrate noninferiority. In leading to a higher rate of vaginal deliveries, more rapid vaginal delivery, and fewer cesareans for fetal issues, vaginal misoprostol may be superior to buccal misoprostol for cervical ripening at term.

Buccal versus Vaginal Misoprostol for Term Induction of Labor: A Retrospective Cohort Study

OBJECTIVE

To compare the efficacy of similar buccal and vaginal misoprostol doses for induction of labor.

STUDY DESIGN

Retrospective chart review of 207 consecutive women undergoing term induction of labor with misoprostol. Misoprostol route and dosing were collected. Time to delivery and other labor outcomes (e.g., vaginal delivery less than 24 hours) were compared between women receiving buccal and vaginal misoprostol.

RESULTS

There was no significant difference in time to delivery for women receiving buccal (median 18.2 hour, 95% confidence interval [CI] = [14.9, 21.5]) versus vaginal (median 18.3 hour, 95% CI = [15.0, 20.4]) misoprostol (p = 0.428); even after adjusting for covariates (p = 0.381). Women who presented with premature rupture of membranes were more likely to receive buccal misoprostol (92.7% received buccal vs. 7.3% received vaginal, p < 0.001). A similar number of women delivered vaginally in the buccal group (88.2%) and vaginal misoprostol group (86.8%, p = 0.835). The proportion of women who experienced uterine tachysystole or chorioamnionitis did not significantly differ by route of administration.

CONCLUSION

We found no significant differences in time to delivery or other labor outcomes between buccal or vaginal dosing of misoprostol in women undergoing labor induction at term.

Comparison between vaginal and sublingual misoprostol 50 µg for cervical ripening prior to induction of labor: randomized clinical trial

OBJECTIVE

To compare the effectiveness and safety of sublingual versus vaginal misoprostol on improving the Bishop score after 6 h of administration.

METHODS

Randomized clinical trial which includes pregnant women in gestational ages from 32/0 to 41/6, with indication of induction of labor with misoprostol. Bishop score was assessed at the time of induction and 6 h after administration of 50 µg misoprostol. Analysis was made over difference in mean Bishop score of 2 points, using a standard deviation of 2, with 90% power, reaching a 95% confidence interval.

RESULTS

102 patients were studied, 51 received sublingual misoprostol, and 51 received vaginal misoprostol. There was a statistically significant difference in cervical modifications in global terms regardless of the administration route at 6 h (P < 0.05). When analyzing each group, there was no significant difference for the mean and standard deviation for Bishop score for sublingual and vaginal route (P = 0.761). There was no significant difference in terms of mode of delivery, Apgar score, cord pH, nor in the presence of complications.

CONCLUSION

There is no statistically significant difference in terms of administration route for cervical ripening using misoprostol 50 µg, whether it was sublingual or vaginal.

TRIAL REGISTRATION NUMBER

NCT02732522. Registry website: https://clinicaltrials.gov/ .

Comparison of the efficacy and safety of sublingual misoprostol with that of vaginal misoprostol for labour induction at term

OBJECTIVE

To compare the efficacy and safety of 50 mcg of sublingual misoprostol with 25 mcg of vaginal misoprostol for induction of labour at term.

METHOD

Non blinded randomized prospective control study. 200 women with singleton term pregnancy, admitted for induction of labour, were randomized to receive either 25 mcg of vaginal misoprostol or 50 mcg of sublingual misoprostol. Outcome measures compared were the number of vaginal deliveries, induction-delivery interval, caesarean section for foetal distress, oxytocin for acceleration, number of doses required, side effects and neonatal outcome.

RESULT

Mean dose was smaller and induction to delivery interval was significantly shorter in the sublingual group (13.1 ± 4.1 h) compared with the vaginal group (17.9 ± 5.4 h), p value 0.001. There were no statistically significant differences in the other secondary outcome measures.

CONCLUSION

50 mcg of sublingual misoprostol was more effective than and as safe as 25 mcg vaginal misoprostol for labour induction at term.

Reduction in caesarean delivery with fetal heart rate monitoring and intermittent pulse oximetry after induction of labour with misoprostol

OBJECTIVE

To integrate intermittent fetal pulse oximetry (FPO) to intrapartum fetal assessment and reduce the rate of caesarean sections.

METHODS

A randomised controlled trial using 37 weeks as a restriction point was conducted in 230 women induced with misoprostol. One hundred-fourteen were assessed with intermittent FPO plus fetal heart rate (FHR) monitoring (study group) and 116 were assessed with FHR monitoring alone (control group). The primary outcome measure was caesarean delivery rates. Secondary outcome measures included induction to delivery interval, number of emergency caesarean deliveries performed for fetal non-reassuring FHR patterns and neonatal outcomes.

RESULTS

There was a reduction both in the overall caesarean deliveries (study n = 18, (15.7%); vs. control n = 31 (26.7%); p = 0.04), and the rate of caesarean deliveries performed for non-reassuring fetal status in the study group (study n = 11, (9.6%); vs. control n = 23 (19.8%); p = 0.03). Induction to delivery interval was similar in between the groups (759 +/- 481 min in group 1; vs. 735 +/- 453 min in group 2 respectively; p = 0.69).

CONCLUSION

Intermittent FPO in misoprostol induced deliveries decreases both total caesarean rate and the caesarean rate due to non-reassuring FHR patterns.

A randomised comparison of patient satisfaction with vaginal and sublingual misoprostol for induction of labour at term*

OBJECTIVE

To compare patient satisfaction with two routes of misoprostol for term labour induction.

DESIGN

Prospective randomised trial.

SETTING

Tertiary care hospital.

POPULATION

A total of 170 women admitted at > or = 37 weeks of gestation for induction of labour.

METHODS

Women were randomised to receive 50 micrograms of either sublingual or vaginal misoprostol.

MAIN OUTCOME MEASURES

Patient satisfaction with the route of administration.

RESULTS

Despite a similar proportion reporting the labour induction as more painful than expected in both groups, a significantly lower proportion mentioned that the pelvic examinations were very painful in the sublingual group (19.7 versus 36.1%, relative risk [RR] 0.5, 95% CI 0.3-0.9). Request for analgesia was similar in both groups. More women in the sublingual group thought that the labour experience was better than expected (RR 2.0, 95% CI 1.2-3.3), had a positive attitude towards induction in subsequent pregnancies (RR 1.6, 95% CI 1.1-2.3) and preferred the same route in subsequent pregnancies (RR 3.1, 95% CI 2.2-4.5). Mean number of misoprostol doses, oxytocin augmentation, tachysystole and hyperstimulation, induction to vaginal delivery interval, vaginal delivery after a single dose, vaginal birth within 12 and 24 hours, and caesarean delivery rates were similar in both groups.

CONCLUSION

Sublingual misoprostol (50 micrograms) is associated with a significantly higher patient satisfaction rate compared with a similar dose of vaginal misoprostol. Sublingual administration offers additional choice to women, in particular those wishing to avoid vaginal administration.

Sublingual compared with vaginal misoprostol for labour induction at term: a randomised controlled trial

OBJECTIVE

To compare the efficacy and safety of 50 microg of sublingual misoprostol with 25 microg of vaginal misoprostol administered for labour induction at term. Design Double-blinded, randomised controlled trial. Setting University Hospital, Kaunas, Lithuania. Sample A total of 140 women at term with indications for labour induction. Methods Women were randomised to receive either 50 microg of sublingual misoprostol with vaginal placebo (n = 70) or sublingual placebo with 25 microg of vaginal misoprostol (n = 70) every 4 hours (maximum six doses). Main outcome measures The number of women delivering vaginally within 24 hours of labour induction. Results Fifty-eight women (83%) in the sublingual misoprostol group and 53 (76%) in the vaginal misoprostol group delivered vaginally within 24 hours [relative risk (RR) 1.1, 95% confidential interval (CI) 0.9-1.3]. However, the induction to vaginal delivery time was significantly shorter in the sublingual group (15.0 +/- 3.7 hours) compared with the vaginal group (16.7 +/- 4.1 hours, P = 0.03). The incidence of tachysystole was more than three-fold higher in the sublingual than in the vaginal group (14 versus 4.3%; RR 3.3, 95% CI 0.9-11.6), but this was not statistically significant. There were no significant differences in the incidence of hypertonus or hyperstimulation syndrome, mode of delivery, interventions for fetal distress or neonatal outcomes between the two groups. Conclusion A 50 microg of sublingual misoprostol 4 hourly for labour induction at term seems to have similar efficacy as 25 microg of vaginal misoprostol. Further studies on safety with larger numbers of women need to be conducted before routine sublingual misoprostol use in this setting.

Sublingual vs. vaginal misoprostol for induction of labor

OBJECTIVE

To compare sublingual with vaginal misoprostol for the induction of labor.

METHODS

This double-blind clinical trial randomized 150 women to receive every 6 h 25 mug of sublingual misoprostol and vaginal placebo or 25 mug of vaginal misoprostol and sublingual placebo. Maternal and neonatal outcomes were analyzed and risk ratios (RRs) with 95% confidence intervals (CIs) calculated. The significance level was 5%.

RESULTS

Vaginal delivery rates were 57% in the sublingual group and 69% in the vaginal group (RR, 0.8; 95% CI, 0.6-1.1). There were 11 cases of fetal distress in the sublingual group and 4 cases in the vaginal group (RR, 2.7; 95% CI, 0.9-8.2). There were no significant differences in the number of doses needed, interval between first dose and delivery, incidence of contractility disturbances, or neonatal results.

CONCLUSION

The administration of misoprostol 25 mug by the sublingual route was neither more effective nor safer than the same dose administered vaginally.

Buccal or sublingual misoprostol for cervical ripening and induction of labour

BACKGROUND

This is one of a series of reviews of cervical ripening and labour induction using standardised methodology. Misoprostol administered by the oral and sublingual routes have the advantage of rapid onset of action, while the sublingual and vaginal routes have the advantage of prolonged activity and greatest bioavailability.

OBJECTIVES

To determine the effectiveness and safety of misoprostol administered buccally or sublingually for third trimester cervical ripening and induction of labour.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (8 December 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 4, 2003), and bibliographies of relevant papers.

SELECTION CRITERIA

Randomised controlled trials comparing buccal or sublingual misoprostol used for third trimester cervical ripening or labour induction with placebo/no treatment or other methods listed above it on a predefined list of labour induction methods.

DATA COLLECTION AND ANALYSIS

A generic strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. Data were extracted onto standardized forms, checked for accuracy, and analysed using RevMan software.

MAIN RESULTS

Three studies (502 participants) compared buccal/sublingual misoprostol respectively with a vaginal regimen (200 microg versus 50 microg) and with oral administration (50 versus 50 microg and 50 versus 100microg).The buccal route was associated with a trend to fewer caesarean sections than with the vaginal route (18/73 versus 28/79; relative risk (RR) 0.70; 95% confidence interval (CI) 0.42 to 1.15). There were no significant differences in any other outcomes. When the same dosage was used sublingually versus orally, the sublingual route was associated with less failures to achieve vaginal delivery within 24 hours (12/50 versus 19/50; RR 0.63, 95% CI 0.34 to 1.16), reduced oxytocin augmentation (17/50 versus 23/50; RR 0.74, 95% CI 0.45 to 1.21) and reduced caesarean section (8/50 versus 15/50; RR 0.53, 95% CI 0.25 to 1.14), but the differences were not statistically significant. When a smaller dose was used sublingually than orally, there were no differences in any of the outcomes.

REVIEWERS' CONCLUSIONS

Based on only three small trials, sublingual misoprostol appears to be at least as effective as when the same dose is administered orally. There are inadequate data to comment on the relative complications and side-effects. Sublingual or buccal misoprostol should not enter clinical use until its safety and optimal dosage have been established by larger trials.