Outpatient balloon catheter vs inpatient prostaglandin for induction of labour (OBLIGE): a randomised controlled trial

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 We systematically identified published and unpublished randomised controlled trials that completed data collection between March 19, 2019, and May 1, 2021, by searching the Cochrane Library, ClinicalTrials.gov,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

Outpatient Induction of Labor - Are Balloon Catheters an Appropriate Method?

As the number of labor inductions in high-income countries has steadily risen, hospital costs and the additional burden on obstetric staff have also increased. Outpatient induction of labor is therefore becoming increasingly important. It has been estimated that 20 - 50% of all pregnant women requiring induction would be eligible for outpatient induction. The use of balloon catheters in patients with an unripe cervix has been shown to be an effective and safe method of cervical priming. Balloon catheters are as effective as the vaginal administration of prostaglandin E 2 or oral misoprostol. The advantage of using a balloon catheter is that it avoids uterine hyperstimulation and monitoring is less expensive. This makes balloon catheters a suitable option for outpatient cervical ripening. Admittedly, intravenous administration of oxytocin to induce or augment labor is required in approximately 75% of cases. Balloon catheters are not associated with a higher risk of maternal and neonatal infection compared to vaginal PGE 2 . Low-risk pregnancies (e.g., post-term pregnancies, gestational diabetes) are suitable for outpatient cervical ripening with a balloon catheter. The data for high-risk pregnancies are still insufficient. The following conditions are recommended when considering an outpatient approach: strict selection of appropriate patients (singleton pregnancy, cephalic presentation, intact membranes), CTG monitoring for 20 - 40 minutes after balloon placement, the patient must be given detailed instructions about the indications for immediate readmission to hospital, and 24-hour phone access to the hospital must be ensured. According to reviewed studies, the balloon catheter remained in place between 12 hours ("overnight") and 24 hours. The most common reason for readmission to hospital was expulsion of the balloon catheter. The advantages of outpatient versus inpatient induction of cervical ripening with a balloon catheter were the significantly shorter hospital stay, the lower costs, and higher patient satisfaction, with both procedures having been shown to be equally effective. Complication rates (e.g., vaginal bleeding, severe pain, uterine hyperstimulation syndrome) during the cervical ripening phase are low (0.3 - 1.5%); severe adverse outcomes (e.g., placental abruption) have not been reported. Compared to inpatient induction of labor using vaginal PGE 2 , outpatient cervical ripening using a balloon catheter had a lower rate of deliveries/24 hours and a significantly higher need for oxytocin; however, hospital stay was significantly shorter, frequency of pain during the cervical ripening phase was significantly lower, and patients' duration of sleep was longer. A randomized controlled study comparing outpatient cervical priming with a balloon catheter with outpatient or inpatient induction of labor with oral misoprostol would be of clinical interest.

Effectiveness of Dinoprostone and Cook's Balloon for Labor Induction in Primipara Women at Term

Labor induction is commonly used for achieving successful vaginal delivery. This study aimed to compare the effectiveness of dinoprostone and Cook's balloon as labor-inducing agents in primipara women at term. A retrospective cohort study among primipara women was conducted in Hubei Maternity and Child Health Hospital. Basic clinical characteristics were collected. The main outcomes were vaginal delivery rate, cesarean section rate and forceps delivery rate. Obstetric and perinatal outcomes were also compared. Univariate and multivariate analyses were further performed to evaluate the predictors for vaginal delivery within 24 h. A total of 845 eligible primipara women undergoing labor induction were recruited. Of them, 141 women were induced with dinoprostone (dinoprostone group, DG), and 704 with Cook's balloon (Cook's balloon group, CG). Groups were homogeneous except more women with premature rupture of membranes in DG, with gestational hypertension in CG (P<0.05). The vaginal delivery rate within 12 h was 1.98% and 16.52% in CG and DG respectively (P=0.0001). Besides, the vaginal delivery rate within 24 h was 37.62% and 52.26% in CG and DG respectively (P=0.0079). DG showed the lower rate of oxytocin augmentation, artificial rupture of membrane and postpartum hemorrhage and the shorter interval from insertion to active labor than CG (P<0.05). Multivariate regression analysis revealed that abortion history, oxytocin augmentation, artificial rupture of membrane, and obstetric analgesia were independent predictors for vaginal delivery within 24 h. In conclusion, dinoprostone was more effective than Cook's balloon to induce labor and achieve vaginal birth in the sample of primipara women at term.

Home versus inpatient induction of labour for improving birth outcomes

BACKGROUND

The setting in which induction of labour takes place (home or inpatient) is likely to have implications for safety, women's experiences and costs. Home induction may be started at home with the subsequent active phase of labour happening either at home or in a healthcare facility (hospital, birth centre, midwifery-led unit). More commonly, home induction starts in a healthcare facility, then the woman goes home to await the start of labour. Inpatient induction takes place in a healthcare facility where the woman stays while awaiting the start of labour.

OBJECTIVES

To assess the effects on neonatal and maternal outcomes of third trimester home induction of labour compared with inpatient induction using the same method of induction.

SEARCH METHODS

For this update, we searched the Cochrane Pregnancy and Childbirth Group's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (31 January 2020)), and reference lists of retrieved studies.

SELECTION CRITERIA

Published and unpublished randomised controlled trials (RCTs) in which home and inpatient settings for induction have been compared. We included conference abstracts but excluded quasi-randomised trials and cross-over studies.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study reports for inclusion. Two review authors carried out data extraction and assessment of risk of bias independently. GRADE assessments were checked by a third review author.

MAIN RESULTS

We included seven RCTs, six of which provided data on 1610 women and their babies. Studies were undertaken between 1998 and 2015, and all were in high- or upper-middle income countries. Most women were induced for post dates. Three studies reported government funding, one reported no funding and three did not report on their funding source. Most GRADE assessments gave very low-certainty evidence, downgrading mostly for high risk of bias and serious imprecision. 1. Home compared to inpatient induction with vaginal prostaglandin E (PGE) (two RCTs, 1028 women and babies; 1022 providing data). Although women's satisfaction may be slightly better in home settings, the evidence is very uncertain (mean difference (MD) 0.16, 95% confidence interval (CI) -0.02 to 0.34, 1 study, 399 women), very low-certainty evidence. There may be little or no difference between home and inpatient induction for other primary outcomes, with all evidence being very low certainty: - spontaneous vaginal birth (average risk ratio (RR) [aRR] 0.91, 95% CI 0.69 to 1.21, 2 studies, 1022 women, random-effects method); - uterine hyperstimulation (RR 1.19, 95% CI 0.40 to 3.50, 1 study, 821 women); - caesarean birth (RR 1.01, 95% CI 0.81 to 1.28, 2 studies, 1022 women); - neonatal infection (RR 1.29, 95% CI 0.59 to 2.82, 1 study, 821 babies); - admission to neonatal intensive care unit (NICU) (RR 1.20, 95% CI 0.50 to 2.90, 2 studies, 1022 babies). Studies did not report serious neonatal morbidity or mortality. 2. Home compared to inpatient induction with controlled release PGE (one RCT, 299 women and babies providing data). There was no information on whether the questionnaire on women's satisfaction with care used a validated instrument, but the findings presented showed no overall difference in scores. We found little or no difference between the groups for other primary outcomes, all also being very low-certainty evidence: - spontaneous vaginal birth (RR 0.94, 95% CI 0.77 to 1.14, 1 study, 299 women); - uterine hyperstimulation (RR 1.01, 95% CI 0.51 to 1.98, 1 study, 299 women); - caesarean births (RR 0.95, 95% CI 0.64 to 1.42, 1 study, 299 women); - admission to NICU (RR 1.38, 0.57 to 3.34, 1 study, 299 babies). The study did not report on neonatal infection nor serious neonatal morbidity or mortality. 3. Home compared to inpatient induction with balloon or Foley catheter (four RCTs; three studies, 289 women and babies providing data). It was again unclear whether questionnaires reporting women's experiences/satisfaction with care were validated instruments, with one study (48 women, 69% response rate) finding women were similarly satisfied. Home inductions may reduce the number of caesarean births, but the data are also compatible with a slight increase and are of very low-certainty (RR 0.64, 95% CI 0.41 to 1.01, 2 studies, 159 women). There was little or no difference between the groups for other primary outcomes with all being very low-certainty evidence: - spontaneous vaginal birth (RR 1.04, 95% CI 0.54 to 1.98, 1 study, 48 women): - uterine hyperstimulation (RR 0.45, 95% CI 0.03 to 6.79, 1 study, 48 women); - admission to NICU (RR 0.37, 95% CI 0.07 to 1.86, 2 studies, 159 babies). There were no serious neonatal infections nor serious neonatal morbidity or mortality in the one study (involving 48 babies) assessing these outcomes.

AUTHORS' CONCLUSIONS

Data on the effectiveness, safety and women's experiences of home versus inpatient induction of labour are limited and of very low-certainty. Given that serious adverse events are likely to be extremely rare, the safety data are more likely to come from very large observational cohort studies rather than relatively small RCTs.