Comparison of labor induction with misoprostol vs. oxytocin/prostaglandin E2 in term pregnancy

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.

Oral Misoprostol Solution for Induction of Labour

OBJECTIVE

To determine the effects of oral misoprostol solution for induction of labour.

STUDY DESIGN

This is a prospective observational study.

SETTING

This study was conducted in Government Medical College, Aurangabad.

METHOD

Patients undergoing induction of labour after 36 weeks of pregnancy were allocated by randomization to induction of labour with oral misoprostol solution administered 2 h apart. Delivery within 24 h after induction with oral misoprostol solution was the primary outcome on which the sample size was based. The data were analysed by Statistical Software for Social Sciences software.

RESULT

Two hundred patients were randomly selected for induction with oral misoprostol solution. There were no significant differences in substantive outcomes. Vaginal delivery within 24 h was achieved in 80.5 % of patients. The caesarean section rate was 19.5 %. Uterine hyperactivity occurred in 4 % of patients. The response to induction of labour in women with unfavourable cervices (modified Bishop's score <2) was somewhat slower with misoprostol, induction to delivery interval was more, oxytocin requirement was more, and vaginal delivery rate was less.

CONCLUSION

This new approach to oral misoprostol solution administration was successful in achieving vaginal delivery rate in 24 h in 80.5 % of patients; rate of LSCS was less 19.5 %.

Induction of labor--pharmacology methods

Pharmacologic methods for induction of labor have been used for many decades. Pharmacologic agents have an advantage over mechanical methods in that they can be used during both the initial cervical ripening stage of induction and throughout the second stage of labor. Pharmacologic induction agents such as prostaglandins and oxytocin are commonly used for labor and delivery floors and are well established for use in cervical ripening. Nitric oxide donors and mifepristone are known agents in medicine but are new and actively studied in the area of cervical ripening. These agents are introduced and analyzed in this review.

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.

Vaginal misoprostol for cervical ripening and induction of labour

BACKGROUND

Misoprostol (Cytotec, Searle) is a prostaglandin E1 analogue widely used for off-label indications such as induction of abortion and of labour. This is one of a series of reviews of methods of cervical ripening and labour induction using standardised methodology.

OBJECTIVES

To determine the effects of vaginal misoprostol for third trimester cervical ripening or induction of labour.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group's Trials Register (November 2008) and bibliographies of relevant papers. We updated this search on 30 April 2010 and added the results to the awaiting classification section.

SELECTION CRITERIA

Clinical trials comparing vaginal 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

We developed a strategy to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction.We used fixed-effect Mantel-Haenszel meta-analysis for combining dichotomous data.If we identified substantial heterogeneity (I² greater than 50%), we used a random-effects method.

MAIN RESULTS

We included 121 trials. The risk of bias must be kept in mind as only 13 trials were double blind.Compared to placebo, misoprostol was associated with reduced failure to achieve vaginal delivery within 24 hours (average relative risk (RR) 0.51, 95% confidence interval (CI) 0.37 to 0.71). Uterine hyperstimulation, without fetal heart rate (FHR) changes, was increased (RR 3.52 95% CI 1.78 to 6.99).Compared with vaginal prostaglandin E2, intracervical prostaglandin E2 and oxytocin, vaginal misoprostol was associated with less epidural analgesia use, fewer failures to achieve vaginal delivery within 24 hours and more uterine hyperstimulation. Compared with vaginal or intracervical prostaglandin E2, oxytocin augmentation was less common with misoprostol and meconium-stained liquor more common.Lower doses of misoprostol compared to higher doses were associated with more need for oxytocin augmentation and less uterine hyperstimulation, with and without FHR changes.We found no information on women's views.

AUTHORS' CONCLUSIONS

Vaginal misoprostol in doses above 25 mcg four-hourly was more effective than conventional methods of labour induction, but with more uterine hyperstimulation. Lower doses were similar to conventional methods in effectiveness and risks. The authors request information on cases of uterine rupture known to readers. The vaginal route should not be researched further as another Cochrane review has shown that the oral route of administration is preferable to the vaginal route. Professional and governmental bodies should agree guidelines for the use of misoprostol, based on the best available evidence and local circumstances.

Vaginal Misoprostol versus high dose of oxytocin for labor induction: a comparative study

To compare the efficacy and complications of intravaginal Misoprostol with oxytocin for induction of labor this study was carried out. One hundred and ten term pregnant women with Bishop score of < or = 4 were randomized into two groups. Fifty five patients received 50 microg intravaginal Misoprostol 2 times at 6 h intervals (Misoprostol group), the second group received oxytocin infusion (6 mu min(-1)) for induction of labor (oxytocin group n = 55). The time from induction to delivery, the route of delivery, fetal outcome and maternal complications were recorded. There was no statistically significant difference regarding demographic or clinical characteristics between two groups. Induction success within the first 12 h were 80 and 33.3% for Misoprostol and oxytocin groups respectively (p<0.05). The average time from induction to delivery was 10. 6 +/- 3.7 and 17 +/- 7.2 h in the Misoprostol and oxytocin administered groups, respectively (p<0.05). The rate of vaginal delivery was significantly higher in misoprostol group (72.7%) when compared with oxytocin group (45.5%). Low Apgar score, meconium stain amniotic fluid, abnormal FHR and precipitating labor was similar in both groups (p>0.05). We concluded misoprostol 50 microg vaginally (every 6 h, up to 100 microg) safely and effectively induces labor and it is recommended for parturient women with Bishop score < or = 4 and the use of this drug could produce several beneficial effects, particularly a decrease in the incidence of cesarean delivery.

Misoprostol compared with prostaglandin E2 for labour induction in women at term with intact membranes and unfavourable cervix: a systematic review*

BACKGROUND

Misoprostol is a commonly used prostaglandin to induce labour. A potential risk of induction, however, is caesarean delivery, especially in women with an unfavourable cervix.

OBJECTIVES

To evaluate the use of misoprostol, compared with prostaglandin E2 (PgE2), for labour induction in women at term with an unfavourable cervix and intact membranes.

SEARCH STRATEGY

PubMed, Medline, EMBASE and the Cochrane Library were searched for articles published in any language from January 1987 to December 2005, using the keywords 'misoprostol', 'labour/labor' and 'induction'.

SELECTION CRITERIA

We identified randomised trials of women at term (> or =37 weeks of gestation) with intact membranes and unfavourable cervix, undergoing labour induction with misoprostol, orally, vaginally, sublingually or buccally, compared with PgE2 vaginally or intracervically.

DATA COLLECTION AND ANALYSIS

Caesarean delivery was the primary outcome, with tachysystole and hyperstimulation as secondary outcomes. The primary analysis compared any misoprostol with any PgE2 for all women, with a subgroup analysis for nulliparous women. Secondary analyses compared different routes and doses of misoprostol (oral or vaginal and 25 microgram or >25 microgram) and PgE2 (intracervical or vaginal). Relative risks (RR) and 95% confidence intervals (CI) were calculated using random effects models. Main results Fourteen of 611 articles identified met the criteria for systematic review, with three providing information for nulliparous women. There was no difference in the risk of caesarean delivery between misoprostol and PgE2 groups (RR = 0.99, 95% CI = 0.83-1.17). Any misoprostol was associated with higher risks of tachysystole and hyperstimulation compared with any PgE2 (RR = 1.86, 95% CI = 1.01-3.43 and RR = 3.71, 95% CI = 2.00-6.88, respectively). There was a higher rate of vaginal delivery within 24 hours among all vaginal deliveries with any misoprostol compared with any PgE2 (RR = 1.14, 95% CI = 1.00-1.31), and among all deliveries, a lower rate of oxytocin use (RR = 0.71, 95% CI = 0.60-0.85) but a trend towards increased meconium staining was observed (RR = 1.22, 95% CI = 0.96-1.55). The use of misoprostol at starting dosages >25 microgram had similar findings to the primary analysis. Studies of lower misoprostol dosing (starting dose of 25 microgram) did not show any differences in the outcomes of interest, but the sample size of this secondary analysis was small (304 women, 155 receiving misoprostol).

AUTHOR'S CONCLUSIONS

Although misoprostol in women at term with an unfavourable cervix and intact membranes was more effective than PgE2 in achieving vaginal delivery within 24 hours, misoprostol does not reduce the rate of caesarean delivery either in all women or in the subgroup of nulliparous women, and it increases the rates of tachysystole and hyperstimulation. Further studies of misoprostol using a starting dose of 25 microgram may be warranted.

Vaginal Misoprostol Administration for Cervical Ripening and Labor Induction

Intravaginal misoprostol has been shown to be an effective agent for cervical ripening and induction of labor. Vaginal application of misoprostol has been reported in over 9000 women worldwide and seems to have safety profile similar to that of endocervically and intravaginally administered dinoprostone. Concern arises with the use of higher doses of intravaginal misoprostol (50 mcg or more) and the association with uterine contractile abnormalities and for this reason, use of low-dose misoprostol regimen has been recommended by the American College of Obstetricians and Gynecologists. The recommendation is use of a 25-mcg dose of misoprostol inserted into the posterior vaginal fornix and repeated every 3 to 6 hours as needed. Misoprostol administration to women with prior cesarean births seems to increase the likelihood of uterine scar disruption and should not be used in these women. There are reports of uterine rupture in women with unscarred uteri treated with vaginally applied misoprostol. Therefore, all patients need to be monitored adequately after misoprostol administration. Although there is a growing body of data regarding the ambulatory use of intravaginal misoprostol for cervical ripening, its use for this purpose cannot be recommended outside of investigational protocols at this time because of concerns for maternal and neonatal safety.

What Is A Failed Labor Induction?

Criteria for failed labor induction have not been standardized. The increasing prevalence of labor induction and the lack of a definition for failed induction contribute to unnecessary abdominal deliveries. Labor duration, cervical dilation, and uterine activity necessary to attain the active phase are reviewed. A practical definition of failed induction of labor is suggested.

Oral misoprostol for induction of labour

BACKGROUND

Misoprostol is a synthetic prostaglandin that can be given orally or vaginally. In most countries misoprostol has not been licensed for use in pregnancy, but its unlicensed use is common because misoprostol is cheap, stable at room temperature and effective in causing uterine contractions. Oral use of misoprostol may be convenient, but high doses could cause uterine hyperstimulation and uterine rupture which may be life-threatening for both mother and fetus.

OBJECTIVES

To assess the effectiveness and safety of oral misoprostol used for labour induction in women with a viable fetus in the third trimester of pregnancy.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (January 2005).

SELECTION CRITERIA

Randomised trials comparing oral misoprostol versus other methods, placebo or no treatment, given to women with a viable fetus for labour induction.

DATA COLLECTION AND ANALYSIS

Three authors independently assessed trial quality and extracted data, using centrally-designed data sheets.

MAIN RESULTS

Forty-one trials (8606 participants) were included. In four trials comparing oral misoprostol with placebo (474 participants), women using oral misoprostol were less likely to have long labours (relative risk (RR) 0.16, 95% confidence interval (CI) 0.05 to 0.49), needed less oxytocin (RR 0.32, 95% CI 0.24 to 0.43) and had a lower caesarean section rate (RR 0.62, 95% CI 0.40 to 0.96). In nine trials comparing oral misoprostol with vaginal dinoprostone (2627 participants), women given oral misoprostol were less likely to need a caesarean section, but this reduction reached statistical significance only in the subgroup with intact membranes (RR 0.78, 95% CI 0.66 to 0.94). Uterine hyperstimulation was more common after oral misoprostol (RR 1.63, 95% CI 1.09 to 2.44) although this was not associated with any adverse fetal events. Seven trials (1017 participants) compared oral misoprostol with intravenous oxytocin. The only difference between the groups was an increase in meconium-stained liquor in women with ruptured membranes following administration of oral misoprostol (RR 1.72, 95% 1.08 to 2.74). Sixteen trials (3645 participants) compared oral and vaginal misoprostol and found no difference in the primary outcomes. There was less uterine hyperstimulation without fetal heart rate changes in those given oral misoprostol (RR 0.37, 95% 0.23 to 0.59). Oral misoprsotol was associated with increased need for oxytocin augmentation (RR 1.28, 95% 1.11 to 1.48) and more meconium-stained liquor (RR 1.27, 1.01 to 1.60).

AUTHORS' CONCLUSIONS

Oral misoprostol appears to be more effective than placebo and at least as effective as vaginal dinoprostone. However, there remain questions about its safety because of a relatively high rate of uterine hyperstimulation and the lack of appropriate dose ranging studies. In countries where misoprostol remains unlicenced for the induction of labour, many practitioners will prefer the legal protection of using a licenced product like dinoprostone. There is no evidence that misoprostol given orally is inferior to the vaginal route and has lower rates of hyperstimulation. If misoprostol is used orally, the dose should not exceed 50 mcg.

Induction of labor

The rate of labor induction continues to rise significantly in the United States because of a growing use of labor induction for postterm pregnancies and elective induction of labor. Although different types and doses of prostaglandins used for cervical ripening often initiate uterine activity, the principal role of these agents is to soften the unripe cervix independent of uterine activity. Several systematic reviews with meta-analyses have shown that prostaglandins are superior to placebo and oxytocin alone in ripening of the cervix. Numerous studies and meta-analyses have assessed misoprostol's efficacy and safety as a labor induction agent. The most appropriate dose and route of administration has not yet been confirmed.

Misoprostol versus oxytocin for labor induction in term and post-term pregnancy: randomized controlled trial

CONTEXT

Misoprostol, a synthetic E1 methyl analog prostaglandin, is at present receiving attention as a cervical modifier and labor induction agent. However, there is still a need for better determination of its safety and effectiveness.

OBJECTIVE

To compare intravaginal misoprostol versus intravenous oxytocin for cervical ripening and labor induction in pregnant women with unripe cervices.

DESIGN

Randomized controlled trial.

SETTING

The study was performed at the Leonor Mendes de Barros Maternity Hospital between November 1998 and December 2000.

PARTICIPANTS

210 pregnant women with intact membranes and indication for labor induction were selected.

PROCEDURES

The women randomly received 25 g of vaginal misoprostol every 4 hours, not exceeding 8 doses (105 women), or oxytocin in a continuous infusion (105 women).

MAIN MEASUREMENTS

The main parameters measured were: latent period, time from induction to vaginal delivery, delivery route, occurrence of vaginal delivery with time, occurrence of uterine tonus alterations, hypoxia and neonatal morbidity. To verify the statistical significance of the differences between the groups, the chi-squared, Student t and log-rank tests were used.

RESULTS

There were no significant differences between the groups concerning conditions for labor induction, age, parity, race, marital status, family income, initial Bishop Index and number of prenatal visits. The cesarean section rate, latent period and period from induction to vaginal delivery were significantly lower for the misoprostol group. With regard to uterine tonus alterations, tachysystole was significantly more common in the misoprostol group. However, there was no difference in hypoxia and neonatal morbidity between the groups.

CONCLUSION

25 g of misoprostol used vaginally every 4 hours is safer and more efficient for cervical ripening and labor induction than oxytocin.

Vaginal misoprostol for cervical ripening and induction of labour

BACKGROUND

Misoprostol (Cytotec, Searle) is a prostaglandin E1 analogue marketed for use in the prevention and treatment of peptic ulcer disease. It is inexpensive, easily stored at room temperature and has few systemic side effects. It is rapidly absorbed orally and vaginally. Although not registered for such use, misoprostol has been widely used for obstetric and gynaecological indications, such as induction of abortion and of labour. This is one of a series of reviews of methods of cervical ripening and labour induction using standardised methodology.

OBJECTIVES

To determine the effects of vaginal misoprostol for third trimester cervical ripening or induction of labour.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group trials register (October 2002), the Cochrane Controlled Trials Register (The Cochrane Library, Issue 3, 2002) and bibliographies of relevant papers.

SELECTION CRITERIA

The criteria for inclusion included the following: (1) clinical trials comparing vaginal 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; (2) random allocation to the treatment or control group; (3) adequate allocation concealment; (4) violations of allocated management not sufficient to materially affect conclusions; (5) clinically meaningful outcome measures reported; (6) data available for analysis according to the random allocation; (7) missing data insufficient to materially affect the conclusions.

DATA COLLECTION AND ANALYSIS

A strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction. The initial data extraction was done centrally, and incorporated into a series of primary reviews arranged by methods of induction of labour, following a standardised methodology. The data will be extracted from the primary reviews into a series of secondary reviews, arranged by category of woman. To avoid duplication of data in the primary reviews, the labour induction methods have been listed in a specific order, from one to 25. Each primary review includes comparisons between one of the methods (from two to 25) with only those methods above it on the list.

MAIN RESULTS

Sixty-two trials have been included. Compared to placebo, misoprostol was associated with increased cervical ripening (relative risk of unfavourable or unchanged cervix after 12 to 24 hours with misoprostol 0.09, 95% confidence interval (CI) 0.03 to 0.24). It was also associated with reduced failure to achieve vaginal delivery within 24 hours (relative risk (RR) 0.36, 95% CI 0.19 to 0.68). Uterine hyperstimulation, without fetal heart rate changes, was increased (RR 11.7 95% CI 2.78 to 49). Compared with vaginal prostaglandin E2, intracervical prostaglandin E2 and oxytocin, vaginal misoprostol labour induction was associated with less epidural analgesia use, fewer failures to achieve vaginal delivery within 24 hours and more uterine hyperstimulation. Compared with vaginal or intracervical prostaglandin E2, oxytocin augmentation was less common, with misoprostol and meconium-stained liquor more common. Compared with intracervical prostaglandin E2, unchanged or unfavourable cervix after 12 to 24 hours was less common with misoprostol. Lower doses of misoprostol compared to higher doses were associated with more need for oxytocin augmentation, less uterine hyperstimulation, with and without fetal heart rate changes, and a non-significant trend to fewer admissions to neonatal intensive care unit. Use of a gel preparation of misoprostol versus tablet was associated with less hyperstimulation and more use of oxytocin and epidural analgesia. Information on women's views is conspicuously lacking.

REVIEWER'S CONCLUSIONS

Vaginal misoprostol appears to be more effective than conventional methods of cervical ripening and labour induction. The apparent increase in uterine hyperstimulation is of concern. Doses not exceeding 25 mcg four-hourly of concern. Doses not exceeding 25 mcg four-hourly appeared to have similar effectiveness and risk of uterine hyperstimulation to conventional labour inducing methods. The studies reviewed were not large enough to exclude the possibility of rare but serious adverse events, particularly uterine rupture, which has been reported anecdotally following misoprostol use in women with and without previous caesarean section. The authors request information on cases of uterine rupture known to readers. Further research is needed to establish the ideal route of administration and dosage, and safety. Professional and governmental bodies should agree guidelines for the use of misoprostol, based on the best available evidence and local circumstances.

A comparison of 100 microg oral misoprostol every 3 hours and 6 hours for labor induction: a randomized controlled trial

OBJECTIVE

To compare the efficacy and safety of 100 microg oral misoprostol for induction of labor between the regimen of 3 hour and 6 hour interval administration.

METHODS

Singleton pregnancies indicated for induction of labor between 34 and 42 weeks of gestation in the condition of unfavorable cervix (Bishop score < or = 4) and no contraindication for prostaglandins therapy were recruited into the study. All pregnant women were randomly assigned to receive 100 microg oral misoprostol every 3 hours or 6 hours until the cervix was favorable for amniotomy, spontaneous rupture of membranes or active labor occurred.

RESULTS

The mean time interval from induction to vaginal delivery was significantly shorter in the 3 hour interval group, compared with the 6 hour interval group (13.82 +/- 6.98h and 17.66 +/- 7.48h, P = 0.0019). There was no significant difference between the groups with regard to mode of delivery, analgesic requirement, maternal complication and neonatal outcome.

CONCLUSIONS

100 microg oral misoprostol every 3 hours is more effective for labor induction than every 6 hours but there was no difference in mode of delivery, analgesic requirement, maternal complications and neonatal outcome. A dose of 100 microg misoprostol orally every 3 hours seems to be the optimum regimen and the new option for labor induction. However, further study should be performed.

A benefit-risk assessment of misoprostol for cervical ripening and labour induction

Misoprostol, a prostaglandin E(1) analogue, is widely used in the US and other countries for cervical ripening and labour induction. Its use for these indications is not approved by the US Food and Drug Administration (FDA). The manufacturer of misoprostol issued a letter to American healthcare providers in August 2000, cautioning against the use of misoprostol in pregnant women and citing a lack of safety data for its use in obstetrical practice. The only FDA-approved indication in the product labelling is the treatment and prevention of intestinal ulcer disease resulting from nonsteroidal anti-inflammatory drug use. Multiple trials have proven that when applied vaginally, misoprostol is an effective agent for cervical ripening and labour induction in term pregnancy. The use of oxytocin augmentation is reduced when intravaginal misoprostol is used compared with other agents. Misoprostol use in obstetrics carries the added benefits of temperature stability at room temperature, which is unlike other prostaglandin preparations which require refrigeration or freezing, and reduced cost. However, debate continues regarding the optimal dose, dosage regimen, and route of administration. Uterine contraction abnormalities are often found in association with higher misoprostol doses (50 microg or more) given vaginally or orally. Some trials also indicate increased frequencies of meconium passage, neonatal acidaemia and caesarean delivery for fetal distress in women receiving higher doses of vaginally applied misoprostol. However, most trials fail to demonstrate a significant change in the caesarean delivery rate with the use of misoprostol, although a recent meta-analysis indicated that the use of intravaginal misoprostol is associated with a lowering of the caesarean rate when compared with pooled controls. Low-dose misoprostol (25 microg) is an effective agent for cervical ripening and labour induction when used in a judicious and cautious fashion. There are insufficient data to support the widespread use of oral misoprostol for cervical ripening and labor induction. Some trials suggest that this approach may be effective; however, the ideal dose and administration regimen have yet to be defined.

Titrated oral misoprostol solution for induction of labour: a multi-centre, randomised trial

OBJECTIVES

To determine the effects of titrated oral misoprostol solution, compared with vaginal dinoprostone.

STUDY DESIGN

Open, randomised clinical trial.

SETTING

Academic hospitals in South Africa and Liverpool, UK.

METHODS

Women undergoing induction of labour after 34 weeks of pregnancy were allocated by randomised, sealed opaque envelopes, to induction of labour with titrated oral misoprostol solution, or two doses of vaginal dinoprostone (2mg) administered six hours apart. Failure to deliver within 24 hours of randomisation was the primary outcome on which the sample size was based. The data were analysed by intention-to-treat.

RESULTS

Six hundred and ninety-five women were randomly allocated: 346 to oral misoprostol and 349 to vaginal dinoprostone. There were no significant differences in substantive outcomes. Vaginal delivery within 24 hours was not achieved in 38% of women in the oral misoprostol group and 36% in the vaginal dinoprostone group (RR 1.08; 95% CI 0.89-1.31). The caesarean section rates were 16% and 20%, respectively (RR 0.80; 95% CI 0.58-1.11). Hyperstimulation with fetal heart rate changes occurred in 4% of women in the oral misoprostol group and 3% after vaginal dinoprostone (RR 1.32, 95% CI 0.59-2.98). The response to induction of labour in women with unfavourable cervices was somewhat slower with misoprostol when membranes were intact, and with dinoprostone when membranes were ruptured. There were no differences in neonatal outcome between the two groups.

CONCLUSIONS

This new approach to oral misoprostol administration was successful in minimising the risk of uterine hyperstimulation, which has been a feature of misoprostol use for induction of labour, at the expense of a somewhat slower response in women with intact membranes and unfavourable cervices. Misoprostol is not registered for use in pregnant women, and further research is needed to confirm optimal and safe dosages.

Use of misoprostol in obstetrics and gynecology

Misoprostol is prostaglandin E1 analogous and marketed for prevention and treatment of peptic ulcer disease. However, it has been used widely in obstetrics and gynecology practice because of its effectiveness, low cost, stability in light and hot climate conditions, and ease of administration compared with its licensed counterparts--dinoprostone and gemeprost. A large number of studies have shown that misoprostol is effective in first and second trimester abortion, late pregnancy labor induction, and third stage of labor management (misoprostol has not been approved by the U.S. Food and Drug Administration for these indications). Because misoprostol is not registered for such use, it has not undergone the extensive testing for appropriate dosage and safety required for registration. Serious complications such as teratogenesis after failed abortions and uterine rupture during second trimester abortions and third trimester labor induction have been reported as the result of increasingly wide use of misoprostol in obstetric and gynecology practice. There is an urgent need to evaluate all the available data and organize a large randomized trial to determine the safety of its use in obstetric and gynecology practice.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to identify the various uses of misoprostol, to describe the potential complications of misoprostol use and its teratogenic effects, to compare the various routes of administration, and to define the appropriate dose.

Oral misoprostol for induction of labour with a viable fetus

BACKGROUND

Misoprostol is a synthetic prostaglandin which has been used to induce labour. Oral use of the drug misoprostol may be convenient, but an overdose could cause uterine hyperstimulation and precipitate labour which may be life-threatening for both mother and fetus.

OBJECTIVES

The objective of this review was to assess the effects of oral misoprostol used for labour induction in women with a viable fetus.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register.

SELECTION CRITERIA

Randomised trials of oral misoprostol versus any other method, placebo or no treatment given to women with a viable fetus for induction of labour.

DATA COLLECTION AND ANALYSIS

The selection of trials and data extraction were undertaken by one reviewer and independently checked by two other reviewers.

MAIN RESULTS

Five trials were included. In one placebo trial, oral misoprostol reduced the need for oxytocin infusion and shortened delivery time in women with prelabour rupture of membranes at term. In another trial, compared to vaginal prostaglandins, oral misoprostol reduced the need for oxytocin (relative risk 0.62, 95% confidence interval 0.47 to 0.82). Based on two trials, the caesarean section rate with oral misoprostol was 20. 2% (55/272) compared with 15.5% (42/270) for vaginal prostaglandins (relative risk 1.29, 95% confidence interval 0.90 to 1.86). Different doses (100 micrograms three hourly and 200 micrograms six hourly) were used in the two trials that compared oral with vaginal misoprostol. The caesarean section rate was 21.8% in the oral misoprostol group compared with 13.5% for vaginal misoprostol (relative risk 1.62, 95% confidence interval 0.85 to 3.09). The uterine hyperstimulation rate with oral misoprostol was 37.5% (36/96) compared with 28% (25/89) for vaginal misoprostol (relative risk 1.32, 95% confidence interval 0.86 to 2.04). There was significant heterogeneity between these two trials.

REVIEWER'S CONCLUSIONS

Oral misoprostol may be an effective method for labour induction. However clinically effective oral regimens may have an unacceptably high incidence of uterine hyperstimulation and possibly uterine rupture.

Misoprostol for induction of labour: a systematic review

OBJECTIVE

To determine, from the best available evidence, the effectiveness and safety of misoprostol administered vaginally or orally for third trimester cervical ripening or induction of labour.

METHODS

Clinical trials of misoprostol used for cervical ripening or labour induction in the third trimester were identified from the register of randomised trials maintained by the Cochrane Pregnancy and Childbirth Group. All identified trials were considered for inclusion in the review according to a prespecified protocol. Primary outcomes were chosen to address clinical effectiveness (delivery within 24 hours) and safety (uterine hyperstimulation, caesarean section, serious maternal and neonatal morbidity) and were determined a priori. All meta-analyses were based on the intention-to-treat principle. In the absence of heterogeneity the summary statistics have been expressed as typical relative risk (RR) and 95% confidence interval (CI).

RESULTS

Vaginal misoprostol: one small study showed that the use of misoprostol results in more effective cervical ripening and reduced need for oxytocin when compared with placebo. When compared with oxytocin, vaginal misoprostol was more effective for labour induction. The relative risk of failure to achieve vaginal delivery within 24 hours was 0.48 (95% CI 0.35 to 0.66). However, the relative risks for uterine hyperstimulation with and without fetal heart rate abnormalities were 2.54 (95% CI 1.12 to 5.77) and 2.96 (95% CI 2.11 to 4.14), respectively. In three out of four trials which studied women with intact membranes and unfavourable cervices, failure to achieve vaginal delivery within 24 hours was reduced with misoprostol when compared with other prostaglandins (RR 0.71, 95% CI 0.62 to 0.81). Vaginal misoprostol was associated with increased uterine hyperstimulation both without fetal heart rate changes (RR 1.67, 95% CI 1.30 to 2.14) and with associated fetal heart rate changes (RR 1.45, 95% CI 1.04 to 2.04). There was also an increase in meconium stained amniotic fluid following vaginal misoprostol (RR 1.38, 95% CI 1.06 to 1.79). Oral misoprostol: one small trial suggests that, when compared with placebo, oral misoprostol reduces the need for oxytocin and shortens the time between induction and delivery. Compared with other prostaglandins one small trial showed a reduced need for oxytocin with oral misoprostol. Two trials compared oral with vaginal misoprostol using different doses. No significant differences were evident.

CONCLUSIONS

Overall, misoprostol appears to be more effective than conventional methods of cervical ripening and labour induction. Although no differences in perinatal outcome were shown, the studies were not sufficiently large to exclude the possibility of uncommon serious adverse effects. In particular the increase in uterine hyperstimulation with fetal heart rate changes following misoprostol is a matter for concern. It is possible that, if sufficient numbers are studied, an unacceptably high number of serious adverse events including uterine rupture and asphyxial fetal deaths may occur. The data at present are not robust enough to address the issue of safety. Thus, though misoprostol shows promise as a highly effective, inexpensive and convenient agent for labour induction, it cannot be recommended for routine use at this stage. Lower dose misoprostol regimens should be investigated further.

Selecting drugs for the pregnant dental patient

When treating pregnant patients, dental practitioners should avoid prescribing some drugs routinely used for local anesthesia, sedation, analgesia or infection. Dental practitioners need to determine that the potential benefits of the drug required for the mother's dental care outweigh the risks to her fetus. This article briefly reviews the relative risks of therapeutic agents commonly used in dental care to help practitioners select the safest drugs for use by pregnant patients.