Titrated oral misoprostol solution versus vaginal misoprostol for labor induction

Methods for the induction of labor: efficacy and safety

This review assessed the efficacy and safety of pharmacologic agents (prostaglandins, oxytocin, mifepristone, hyaluronidase, and nitric oxide donors) and mechanical methods (single- and double-balloon catheters, laminaria, membrane stripping, and amniotomy) and those generally considered under the rubric of complementary medicine (castor oil, nipple stimulation, sexual intercourse, herbal medicine, and acupuncture). A substantial body of published reports, including 2 large network meta-analyses, support the safety and efficacy of misoprostol (PGE1) when used for cervical ripening and labor induction. Misoprostol administered vaginally at doses of 50 μg has the highest probability of achieving vaginal delivery within 24 hours. Regardless of dosing, route, and schedule of administration, when used for cervical ripening and labor induction, prostaglandin E2 seems to have similar efficacy in decreasing cesarean delivery rates. Globally, although oxytocin represents the most widely used pharmacologic agent for labor induction, its effectiveness is highly dependent on parity and cervical status. Oxytocin is more effective than expectant management in inducing labor, and the efficacy of oxytocin is enhanced when combined with amniotomy. However, prostaglandins administered vaginally or intracervically are more effective in inducing labor than oxytocin. A single 200-mg oral tablet of mifepristone seems to represent the lowest effective dose for cervical ripening. The bulk of the literature assessing relaxin suggests this agent has limited benefit when used for this indication. Although intracervical injection of hyaluronidase may cause cervical ripening, the need for intracervical administration has limited the use of this agent. Concerning the vaginal administration of nitric oxide donors, including isosorbide mononitrate, isosorbide, nitroglycerin, and sodium nitroprusside, the higher incidence of side effects with these agents has limited their use. A synthetic hygroscopic cervical dilator has been found to be effective for preinduction cervical ripening. Although a pharmacologic agent may be administered after the use of the synthetic hygroscopic dilator, in an attempt to reduce the interval to vaginal delivery, concomitant use of mechanical and pharmacologic methods is being explored. Combining the use of a single-balloon catheter with dinoprostone, misoprostol, or oxytocin enhances the efficacy of these pharmacologic agents in cervical ripening and labor induction. The efficacy of single- and double-balloon catheters in cervical ripening and labor induction seems similar. To date, the combination of misoprostol with an intracervical catheter seems to be the best approach when balancing delivery times with safety. Although complementary methods are occasionally used by patients, given the lack of data documenting their efficacy and safety, these methods are rarely used in hospital settings.

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).

Low-dose oral misoprostol for induction of labour

BACKGROUND

Misoprostol given orally is a commonly used labour induction method. Our Cochrane Review is restricted to studies with low-dose misoprostol (initially ≤ 50 µg), as higher doses pose unacceptably high risks of uterine hyperstimulation.

OBJECTIVES

To assess the efficacy and safety of low-dose oral misoprostol for labour induction in women with a viable fetus in the third trimester of pregnancy.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov,  the WHO International Clinical Trials Registry Platform (14 February 2021) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised trials comparing low-dose oral misoprostol (initial dose ≤ 50 µg) versus placebo, vaginal dinoprostone, vaginal misoprostol, oxytocin, or mechanical methods; or comparing oral misoprostol protocols (one- to two-hourly versus four- to six-hourly; 20 µg to 25 µg versus 50 µg; or 20 µg hourly titrated versus 25 µg two-hourly static).

DATA COLLECTION AND ANALYSIS

Using Covidence, two review authors independently screened reports, extracted trial data, and performed quality assessments. Our primary outcomes were vaginal birth within 24 hours, caesarean section, and hyperstimulation with foetal heart changes.

MAIN RESULTS

We included 61 trials involving 20,026 women. GRADE assessments ranged from moderate- to very low-certainty evidence, with downgrading decisions based on imprecision, inconsistency, and study limitations. Oral misoprostol versus placebo/no treatment (four trials; 594 women) Oral misoprostol may make little to no difference in the rate of caesarean section (risk ratio (RR) 0.81, 95% confidence interval (CI) 0.59 to 1.11; 4 trials; 594 women; moderate-certainty evidence), while its effect on uterine hyperstimulation with foetal heart rate changes is uncertain (RR 5.15, 95% CI 0.25 to 105.31; 3 trials; 495 women; very low-certainty evidence). Vaginal births within 24 hours was not reported. In all trials, oxytocin could be commenced after 12 to 24 hours and all women had pre-labour ruptured membranes. Oral misoprostol versus vaginal dinoprostone (13 trials; 9676 women) Oral misoprostol probably results in fewer caesarean sections (RR 0.84, 95% CI 0.78 to 0.90; 13 trials, 9676 women; moderate-certainty evidence). Subgroup analysis indicated that 10 µg to 25 µg (RR 0.80, 95% CI 0.74 to 0.87; 9 trials; 8652 women) may differ from 50 µg (RR 1.10, 95% CI 0.91 to 1.34; 4 trials; 1024 women) for caesarean section. Oral misoprostol may decrease vaginal births within 24 hours (RR 0.93, 95% CI 0.87 to 1.00; 10 trials; 8983 women; low-certainty evidence) and hyperstimulation with foetal heart rate changes (RR 0.49, 95% CI 0.40 to 0.59; 11 trials; 9084 women; low-certainty evidence). Oral misoprostol versus vaginal misoprostol (33 trials; 6110 women) Oral use may result in fewer vaginal births within 24 hours (average RR 0.81, 95% CI 0.68 to 0.95; 16 trials, 3451 women; low-certainty evidence), and less hyperstimulation with foetal heart rate changes (RR 0.69, 95% CI 0.53 to 0.92, 25 trials, 4857 women, low-certainty evidence), with subgroup analysis suggesting that 10 µg to 25 µg orally (RR 0.28, 95% CI 0.14 to 0.57; 6 trials, 957 women) may be superior to 50 µg orally (RR 0.82, 95% CI 0.61 to 1.11; 19 trials; 3900 women). Oral misoprostol probably does not increase caesarean sections overall (average RR 1.00, 95% CI 0.86 to 1.16; 32 trials; 5914 women; low-certainty evidence) but likely results in fewer caesareans for foetal distress (RR 0.74, 95% CI 0.55 to 0.99; 24 trials, 4775 women). Oral misoprostol versus intravenous oxytocin (6 trials; 737 women, 200 with ruptured membranes) Misoprostol may make little or no difference to vaginal births within 24 hours (RR 1.12, 95% CI 0.95 to 1.33; 3 trials; 466 women; low-certainty evidence), but probably results in fewer caesarean sections (RR 0.67, 95% CI 0.50 to 0.90; 6 trials; 737 women; moderate-certainty evidence). The effect on hyperstimulation with foetal heart rate changes is uncertain (RR 0.66, 95% CI 0.19 to 2.26; 3 trials, 331 women; very low-certainty evidence). Oral misoprostol versus mechanical methods (6 trials; 2993 women) Six trials compared oral misoprostol to transcervical Foley catheter. Misoprostol may increase vaginal birth within 24 hours (RR 1.32, 95% CI 0.98 to 1.79; 4 trials; 1044 women; low-certainty evidence), and probably reduces the risk of caesarean section (RR 0.84, 95% CI 0.75 to 0.95; 6 trials; 2993 women; moderate-certainty evidence). There may be little or no difference in hyperstimulation with foetal heart rate changes (RR 1.31, 95% CI 0.78 to 2.21; 4 trials; 2828 women; low-certainty evidence). Oral misoprostol one- to two-hourly versus four- to six-hourly (1 trial; 64 women) The evidence on hourly titration was very uncertain due to the low numbers reported. Oral misoprostol 20 µg hourly titrated versus 25 µg two-hourly static (2 trials; 296 women) The difference in regimen may have little or no effect on the rate of vaginal births in 24 hours (RR 0.97, 95% CI 0.80 to 1.16; low-certainty evidence). The evidence is of very low certainty for all other reported outcomes.

AUTHORS' CONCLUSIONS

Low-dose oral misoprostol is probably associated with fewer caesarean sections (and therefore more vaginal births) than vaginal dinoprostone, and lower rates of hyperstimulation with foetal heart rate changes. However, time to birth may be increased, as seen by a reduced number of vaginal births within 24 hours. Compared to transcervical Foley catheter, low-dose oral misoprostol is associated with fewer caesarean sections, but equivalent rates of hyperstimulation. Low-dose misoprostol given orally rather than vaginally is probably associated with similar rates of vaginal birth, although rates may be lower within the first 24 hours. However, there is likely less hyperstimulation with foetal heart changes, and fewer caesarean sections performed due to foetal distress. The best available evidence suggests that low-dose oral misoprostol probably has many benefits over other methods for labour induction. This review supports the use of low-dose oral misoprostol for induction of labour, and demonstrates the lower risks of hyperstimulation than when misoprostol is given vaginally. More trials are needed to establish the optimum oral misoprostol regimen, but these findings suggest that a starting dose of 25 µg may offer a good balance of efficacy and safety.

Challenges and Limitations of Clinical Trials on Labor Induction: A Review of the Literature

Induction of labor is a common obstetric procedure performed in nearly a quarter of all deliveries in the United States. Pharmacological (prostaglandins, oxytocin) and/or mechanical methods (balloon catheters) are commonly used for labor induction; however, there is ongoing debate as to which method is the safest and most effective. This narrative review discusses key limitations of published trials on labor induction, including the lack of well-designed randomized controlled trials directly comparing specific methods of induction, heterogeneous trial populations, and wide variation in the protocols used and outcomes reported. Furthermore, the majority of published trials were underpowered to detect significant differences in the most clinically relevant efficacy and safety outcomes (e.g., cesarean delivery, neonatal mortality). By identifying the limitations of labor induction trials, we hope to highlight the importance of quality published data to better inform guidelines and drive evidence-based treatment decisions.

Which method is best for the induction of labour? A systematic review, network meta-analysis and cost-effectiveness analysis

BACKGROUND

More than 150,000 pregnant women in England and Wales have their labour induced each year. Multiple pharmacological, mechanical and complementary methods are available to induce labour.

OBJECTIVE

To assess the relative effectiveness, safety and cost-effectiveness of labour induction methods and, data permitting, effects in different clinical subgroups.

METHODS

We carried out a systematic review using Cochrane methods. The Cochrane Pregnancy and Childbirth Group's Trials Register was searched (March 2014). This contains over 22,000 reports of controlled trials (published from 1923 onwards) retrieved from weekly searches of OVID MEDLINE (1966 to current); Cochrane Central Register of Controlled Trials (The Cochrane Library); EMBASE (1982 to current); Cumulative Index to Nursing and Allied Health Literature (1984 to current); ClinicalTrials.gov; the World Health Organization International Clinical Trials Registry Portal; and hand-searching of relevant conference proceedings and journals. We included randomised controlled trials examining interventions to induce labour compared with placebo, no treatment or other interventions in women eligible for third-trimester induction. We included outcomes relating to efficacy, safety and acceptability to women. In addition, for the economic analysis we searched the Database of Abstracts of Reviews of Effects, and Economic Evaluations Databases, NHS Economic Evaluation Database and the Health Technology Assessment database. We carried out a network meta-analysis (NMA) using all of the available evidence, both direct and indirect, to produce estimates of the relative effects of each treatment compared with others in a network. We developed a de novo decision tree model to estimate the cost-effectiveness of various methods. The costs included were the intervention and other hospital costs incurred (price year 2012-13). We reviewed the literature to identify preference-based utilities for the health-related outcomes in the model. We calculated incremental cost-effectiveness ratios, expected costs, utilities and net benefit. We represent uncertainty in the optimal intervention using cost-effectiveness acceptability curves.

RESULTS

We identified 1190 studies; 611 were eligible for inclusion. The interventions most likely to achieve vaginal delivery (VD) within 24 hours were intravenous oxytocin with amniotomy [posterior rank 2; 95% credible intervals (CrIs) 1 to 9] and higher-dose (≥ 50 µg) vaginal misoprostol (rank 3; 95% CrI 1 to 6). Compared with placebo, several treatments reduced the odds of caesarean section, but we observed considerable uncertainty in treatment rankings. For uterine hyperstimulation, double-balloon catheter had the highest probability of being among the best three treatments, whereas vaginal misoprostol (≥ 50 µg) was most likely to increase the odds of excessive uterine activity. For other safety outcomes there were insufficient data or there was too much uncertainty to identify which treatments performed 'best'. Few studies collected information on women's views. Owing to incomplete reporting of the VD within 24 hours outcome, the cost-effectiveness analysis could compare only 20 interventions. The analysis suggested that most interventions have similar utility and differ mainly in cost. With a caveat of considerable uncertainty, titrated (low-dose) misoprostol solution and buccal/sublingual misoprostol had the highest likelihood of being cost-effective.

LIMITATIONS

There was considerable uncertainty in findings and there were insufficient data for some planned subgroup analyses.

CONCLUSIONS

Overall, misoprostol and oxytocin with amniotomy (for women with favourable cervix) is more successful than other agents in achieving VD within 24 hours. The ranking according to safety of different methods was less clear. The cost-effectiveness analysis suggested that titrated (low-dose) oral misoprostol solution resulted in the highest utility, whereas buccal/sublingual misoprostol had the lowest cost. There was a high degree of uncertainty as to the most cost-effective intervention.

FUTURE WORK

Future trials should be powered to detect a method that is more cost-effective than misoprostol solution and report outcomes included in this NMA.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005116.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Comparative study of titrated oral misoprostol solution and vaginal dinoprostone for labor induction at term pregnancy

OBJECTIVE

To evaluate effectiveness and safety of titrated oral misoprostol solution (OMS) in comparison with vaginal dinoprostone for cervix ripening and labor induction in term pregnant women.

METHODS

A multicenter randomized controlled trial of women with term singleton pregnancy with indications for labor induction; 481 participants were allocated to receive titrated OMS with different doses by hourly administration according to the procedure or insert vaginal dinoprostone for cervix ripening and labor induction to compare maternal outcomes including indication of labor induction, mode of outcome of delivery, maternal morbidity, and neonatal outcomes between two groups for evaluating the efficacy and safety of titrated oral misoprostol induction.

RESULT

Proportion of delivery within 12 h of titrated oral misoprostol is significantly less than vaginal dinoprostone (p = 0.03), but no difference of total vaginal delivery rate (p = 0.93); the mean time of first treatment to vaginal delivery was longer in OMS group (21.3 ± 14.5 h) compared with the vaginal dinoprostone group (15.7 ± 9.6 h). Although the proportion of cesarean section between the two groups showed no statistically significant difference, OMS group showed significantly lower frequency of uterine hyperstimulation, hypertonus, partus precipitatus and non-reassuring fetal heart rate than dinoprostone group. Neonatal outcomes were similar evaluating from Apgar score and NICU admission. Our study also showed that labor induction of women with cervix Bishop score ≤3 needed increased dosage of misoprostol solution.

CONCLUSION

Titrated OMS is as effective as vaginal dinoprostone in labor induction for term pregnant women, with safer effect for its lower rate of adverse effect for women.

Maternal and perinatal outcomes in women with and without hypertensive syndromes submitted to induction of labor with misoprostol

OBJECTIVES

To determine maternal and perinatal outcomes according to the mode of delivery in normotensive and hypertensive women bearing a live, full-term fetus, who were submitted to labor induction with misoprostol.

METHODS

Retrospective cohort study. The endpoints were tachysystole, uterine hyperstimulation, indications for cesarean section, severe maternal morbidity, side effects, maternal death, 1st/5th minute Apgar, neonatal death, requirement for neonatal intensive care, and birth weight (grams). The chi-square or Fisher's exact test was applied at a significance level of 5%. Risk ratios (RRs) and their 95% confidence intervals (95% CI) were calculated.

RESULTS

No significant differences were found in maternal outcome as a function of mode of delivery. First-minute Apgar score <7 was less common with vaginal deliveries in normotensive women (RR = 0.41; 95% CI: 0.18-0.90), this being the only significant difference in perinatal outcome.

CONCLUSION

Maternal and perinatal outcomes were similar in hypertensive and normotensive women submitted to labor induction with misoprostol.

Factors associated with vaginal delivery in hypertensive and normotensive pregnant women submitted to labor induction with misoprostol: a cohort study

OBJECTIVE

To determine the factors associated with vaginal delivery in hypertensive and normotensive pregnant women submitted to induction of labor with misoprostol.

METHODS

A cohort study.

RESULTS

The factors associated with vaginal delivery in both normotensive and hypertensive women were, respectively, Bishop score ≥ 4 (OR = 1.87; 95% CI: 1.06-3.29; p = 0.03) and (OR = 2.31; 95% CI: 1.25-4.28; p = 0.008) and parity ≥ 1 (OR = 4.36; 95% CI: 2.16-8.80; p < 0.0001) and (OR = 2.61; 95% CI: 1.36-5.04; p = 0.004).

CONCLUSION

The factors associated with vaginal delivery were Bishop score ≥ 4 and parity ≥ 1 irrespective of whether or not the women were hypertensive.

Oral misoprostol for induction of labour

BACKGROUND

Misoprostol is an orally active prostaglandin. In most countries misoprostol is not licensed for labour induction, but its use is common because it is cheap and heat stable.

OBJECTIVES

To assess the use of oral misoprostol for labour induction in women with a viable fetus.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (17 January 2014).

SELECTION CRITERIA

Randomised trials comparing oral misoprostol versus placebo or other methods, given to women with a viable fetus for labour induction.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial data, using centrally-designed data sheets.

MAIN RESULTS

Overall there were 76 trials (14,412) women) which were of mixed quality.In nine trials comparing oral misoprostol with placebo (1109 women), women using oral misoprostol were more likely to give birth vaginally within 24 hours (risk ratio (RR) 0.16, 95% confidence interval (CI) 0.05 to 0.49; one trial; 96 women), need less oxytocin (RR 0.42, 95% CI 0.37 to 0.49; seven trials; 933 women) and have a lower caesarean section rate (RR 0.72, 95% CI 0.54 to 0.95; eight trials; 1029 women).In 12 trials comparing oral misoprostol with vaginal dinoprostone (3859 women), women given oral misoprostol were less likely to need a caesarean section (RR 0.88, 95% CI 0.78 to 0.99; 11 trials; 3592 women). There was some evidence that they had slower inductions, but there were no other statistically significant differences.Nine trials (1282 women) compared oral misoprostol with intravenous oxytocin. The caesarean section rate was significantly lower in women who received oral misoprostol (RR 0.77, 95% CI 0.60 to 0.98; nine trials; 1282 women), but they had increased rates of meconium-stained liquor (RR 1.65, 95% CI 1.04 to 2.60; seven trials; 1172 women).Thirty-seven trials (6417 women) compared oral and vaginal misoprostol and found no statistically significant difference in the primary outcomes of serious neonatal morbidity/death or serious maternal morbidity or death. The results for vaginal birth not achieved in 24 hours, uterine hyperstimulation with fetal heart rate (FHR) changes, and caesarean section were highly heterogenous - for uterine hyperstimulation with FHR changes this was related to dosage with lower rates in those with lower doses of oral misoprostol. However, there were fewer babies born with a low Apgar score in the oral group (RR 0.60, 95% CI 0.44 to 0.82; 19 trials; 4009 babies) and a decrease in postpartum haemorrhage (RR 0.57, 95% CI 0.34 to 0.95; 10 trials; 1478 women). However, the oral misoprostol group had an increase in meconium-stained liquor (RR 1.22, 95% CI 1.03 to 1.44; 24 trials; 3634 women).

AUTHORS' CONCLUSIONS

Oral misoprostol as an induction agent is effective at achieving vaginal birth. It is more effective than placebo, as effective as vaginal misoprostol and results in fewer caesarean sections than vaginal dinoprostone or oxytocin.Where misoprostol remains unlicensed for the induction of labour, many practitioners will prefer to use a licensed product like dinoprostone. If using oral misoprostol, the evidence suggests that the dose should be 20 to 25 mcg in solution. Given that safety is the primary concern, the evidence supports the use of oral regimens over vaginal regimens. This is especially important in situations where the risk of ascending infection is high and the lack of staff means that women cannot be intensely monitored.