Balloon catheters versus vaginal prostaglandins for labour induction (CPI Collaborative): an individual participant data meta-analysis of randomised controlled trials

BACKGROUND

Induction of labour is one of the most common obstetric interventions globally. Balloon catheters and vaginal prostaglandins are widely used to ripen the cervix in labour induction. We aimed to compare the effectiveness and safety profiles of these two induction methods.

METHODS

We did an individual participant data meta-analysis comparing balloon catheters and vaginal prostaglandins for cervical ripening before labour induction. We systematically identified published and unpublished randomised controlled trials that completed data collection between March 19, 2019, and May 1, 2021, by searching the Cochrane Library, ClinicalTrials.gov, WHO International Clinical Trials Registry Platform, and PubMed. Further trials done before March 19, 2019, were identified through a recent Cochrane review. Data relating to the combined use of the two methods were not included, only data from women with a viable, singleton pregnancy were analysed, and no exclusion was made based on parity or membrane status. We contacted authors of individuals trials and participant-level data were harmonised and recoded according to predefined definitions of variables. Risk of bias was assessed with the ROB2 tool. The primary outcomes were caesarean delivery, indication for caesarean delivery, a composite adverse perinatal outcome, and a composite adverse maternal outcome. We followed the intention-to-treat principle for the main analysis. The primary meta-analysis used two-stage random-effects models and the sensitivity analysis used one-stage mixed models. All models were adjusted for maternal age and parity. This meta-analysis is registered with PROSPERO (CRD42020179924).

FINDINGS

Individual participant data were available from 12 studies with a total of 5460 participants. Balloon catheters, compared with vaginal prostaglandins, did not lead to a significantly different rate of caesarean delivery (12 trials, 5414 women; crude incidence 27·0%; adjusted OR [aOR] 1·09, 95% CI 0·95-1·24; I²=0%), caesarean delivery for failure to progress (11 trials, 4601 women; aOR 1·20, 95% CI 0·91-1·58; I²=39%), or caesarean delivery for fetal distress (10 trials, 4441 women; aOR 0·86, 95% CI 0·71-1·04; I²=0%). The composite adverse perinatal outcome was lower in women who were allocated to balloon catheters than in those allocated to vaginal prostaglandins (ten trials, 4452 neonates, crude incidence 13·6%; aOR 0·80, 95% CI 0·70-0·92; I²=0%). There was no significant difference in the composite adverse maternal outcome (ten trials, 4326 women, crude incidence 22·7%; aOR 1·02, 95% CI 0·89-1·18; I²=0%).

INTERPRETATION

In induction of labour, balloon catheters and vaginal prostaglandins have comparable caesarean delivery rates and maternal safety profiles, but balloon catheters lead to fewer adverse perinatal events.

FUNDING

Australian National Health and Medical Research Council and Monash Health Emerging Researcher Fellowship.

A randomized controlled trial comparing vaginal misoprostol versus Foley catheter plus oxytocin for labor induction

OBJECTIVE

To compare effectiveness and safety of 25 microg vaginal misoprostol versus Foley catheter and oxytocin for cervical ripening and labor induction in pregnant women with unripe cervices.

DESIGN

Randomized controlled trial.

SETTING

A public maternity in Recife, Brazil.

SAMPLE

A total of 240 pregnant women.

METHODS

Women with a term or post-term, live, singleton fetus in cephalic presentation, intact membranes, Bishop score <6, not in labor, medically indicated for labor induction. They were randomly divided in Group 1, where 119 women received 25 microg of intravaginal misoprostol every 6 hours for a maximum of four doses; and Group 2, where 121 women had a 14-F Foley catheter inserted into their cervical canal. Once past the internal os, the balloon was inflated. Intravenous oxytocin was initiated after the balloon was spontaneously extruded from the cervix or after 24 hours.

RESULTS

There were no significant differences between the groups regarding baseline characteristics. Misoprostol was more effective in inducing labor than Foley catheter and oxytocin. Mean induction-to-vaginal delivery time with misoprostol was shorter (17.3 vs. 20.2 hours, p = 0.016). There were more vaginal deliveries in the misoprostol group at 12 (p < 0.001) and 18 (p = 0.007) hours, but the difference was no longer statistically significant at 24 and 48 hours. There were no significant differences in uterine contraction abnormalities, puerperal infection or neonatal outcomes.

CONCLUSIONS

Vaginal misoprostol is more effective than and as safe as Foley catheter and oxytocin for induction of labor in term and post-term pregnancy.