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

Madeleine N. Jones, Kirsten R. Palmer, Maleesa M. Pathirana, Jose Guilherme Cecatti, Olimpio B.Moraes Filho, Lena Marions, Måns Edlund, Martina Prager, Craig Pennell, Jan E. Dickinson, Nelson Sass, Marta Jozwiak, Mieke Ten Eikelder, Katrien Oude Rengerink, Kitty W.M. Bloemenkamp, Amanda Henry, Ellen C.L. Løkkegaard, Ib Jarle Christensen, Jeff M. Szychowski, Rodney K. EdwardsMichael Beckmann, Caroline Diguisto, Amélie Le Gouge, Franck Perrotin, Ian Symonds, Sean O'Leary, Daniel L. Rolnik, Ben W. Mol, Wentao Li*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


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 We systematically identified published and unpublished randomised controlled trials that completed data collection between March 19, 2019, and May 1, 2021, by searching the Cochrane Library,, WHO International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.

Original languageEnglish
Pages (from-to)1681-1692
Number of pages12
JournalThe Lancet
Issue number10364
Early online date10 Nov 2022
Publication statusPublished - 12 Nov 2022

Bibliographical note

Funding Information:
The research team thanks trial investigators and those working in their trial groups who provided data for analysis, answered queries, and worked with us to understand their datasets. We also wish to thank the women who took part in the trials and made this analysis possible. This research was supported by funding from an NHMRC investigator grant (GNT1176437 for BWM) and a Monash Health Emerging Researcher Fellowship.

Data Availability Statement

The protocol, statistical analysis plan, and codebook are available on request. The trial investigators who shared individual participant data for the purposes of the meta-analysis retain ownership of their trial data and any requests for access to individual participant data should be made directly to them (they can be accessed via email and the email addresses can be found in their original publications which are cited in this manuscript).


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