Maternal and fetal characteristics for predicting risk of Cesarean section following induction of labor: pooled analysis of PROBAAT trials.

OBJECTIVE: Induction of labor (IOL) is one of the most widely used obstetric interventions. However, one-fifth of IOLs result in Cesarean section (CS). We aimed to assess maternal and fetal characteristics that influence the likelihood of CS following IOL, according to the indication for CS. METHODS: This was a secondary analysis of pooled data from four randomized controlled trials, including women undergoing IOL at term who had a singleton pregnancy and an unfavorable cervix, intact membranes and the fetus in cephalic presentation. The main outcomes of this analysis were CS for failure to progress (FTP) and CS for suspected fetal compromise (SFC). Restricted cubic splines were used to determine whether continuous maternal and fetal characteristics had a non-linear relationship with outcome. Optimal cut-offs for those characteristics with a non-linear pattern were determined based on the maximum area under the receiver-operating-characteristics curve. Adjusted odds ratios (aOR) were computed, using multivariable logistic regression analysis, for the associations between optimally categorized characteristics and outcome. RESULTS: Of a total of 2990 women undergoing IOL, 313 (10.5%) had CS for FTP and 227 (7.6%) had CS for SFC. The risk of CS for FTP was increased in women aged 31-35 years compared with younger women (aOR, 1.51 (95% CI, 1.15-1.99)), in nulliparous compared with parous women (aOR, 8.07 (95% CI, 5.34-12.18)) and in Sub-Saharan African compared with Caucasian women (aOR, 2.09 (95% CI, 1.33-3.28)). Higher body mass index (BMI) increased incrementally the risk of CS for FTP (aOR, 1.06 (95% CI, 1.04-1.08)). High birth-weight percentile was also associated with an increased risk of CS due to FTP (aOR, 2.66 (95% CI, 1.74-4.07) for birth weight between the 80.0th and 89.9th percentiles and aOR, 4.08 (95% CI, 2.75-6.05) for birth weight ≥ 90th percentile, as compared with birth weight between the 20.0th and 49.9th percentiles). For CS due to SFC, higher maternal age (aOR, 1.09 (95% CI, 1.05-1.12)) and BMI (aOR, 1.05 (95% CI, 1.03-1.08)) were associated with an incremental increase in risk. The risk of CS for SFC was increased in nulliparous compared with parous women (aOR, 5.91 (95% CI, 3.76-9.28)) and in South Asian compared with Caucasian women (aOR, 2.50 (95% CI, 1.23-5.10)). Birth weight < 10.0th percentile increased significantly the risk of CS due to SFC (aOR, 1.93 (95% CI, 1.22-3.05)), as compared with birth weight between the 20.0th and 49.9th percentiles. Bishop score did not demonstrate a significant association with the risk of CS for FTP or for SFC. CONCLUSIONS: In women undergoing IOL, maternal age, BMI, parity, ethnicity and birth-weight percentile are predictors of CS due to FTP and of CS due to SFC, but the direction and magnitude of the associations differ according to the indication for CS. These characteristics should be considered in combination with the Bishop score to stratify the risk of CS for different indications in women undergoing IOL. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Induction of labor with Foley catheter and risk of subsequent preterm birth: follow-up study of two randomized controlled trials (PROBAAT-1 and -2).

OBJECTIVE: To evaluate the rate of preterm birth (PTB) in a subsequent pregnancy in women who had undergone term induction using a Foley catheter compared with prostaglandins. METHODS: This was a follow-up study of two large randomized controlled trials (PROBAAT-1 and PROBAAT-2). In the original trials, women with a term singleton pregnancy with the fetus in cephalic presentation and with an indication for labor induction were randomized to receive either a 30-mL Foley catheter or prostaglandins (vaginal prostaglandin E2 in PROBAAT-1 and oral misoprostol in PROBAAT-2). Data on subsequent ongoing pregnancies > 16 weeks' gestation were collected from hospital charts from clinics participating in this follow-up study. The main outcome measure was preterm birth < 37 weeks' gestation in a subsequent pregnancy. RESULTS: Fourteen hospitals agreed to participate in this follow-up study. Of the 1142 eligible women, 572 had been allocated to induction of labor using a Foley catheter and 570 to induction of labor using prostaglandins. Of these, 162 (14%) were lost to follow-up. In total, 251 and 258 women had a known subsequent pregnancy > 16 weeks' gestation in the Foley catheter and prostaglandin groups, respectively. There were no differences in baseline characteristics between the groups. The overall rate of PTB in a subsequent pregnancy was 9/251 (3.6%) in the Foley catheter group vs 10/258 (3.9%) in the prostaglandin group (relative risk (RR), 0.93; 95% CI, 0.38-2.24), and the rate of spontaneous PTB was 5/251 (2.0%) vs 5/258 (1.9%) (RR, 1.03; 95% CI, 0.30-3.51). CONCLUSION: In women with term singleton pregnancy, induction of labor using a 30-mL Foley catheter is not associated with an increased risk of PTB in a subsequent pregnancy, as compared to induction of labor using prostaglandins. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Foley catheter vs oral misoprostol for induction of labor: individual participant data meta-analysis.

OBJECTIVE: To compare the effectiveness and safety of Foley catheter and oral misoprostol for induction of labor (IOL). METHODS: The Cochrane Review on Mechanical Methods for Induction of Labour and Ovid MEDLINE, EMBASE via Ovid, Ovid Emcare, CINAHL Plus, ClinicalTrials.gov and Scopus, from inception to April 2019, were searched for randomized controlled trials (RCTs) comparing Foley catheter to oral misoprostol for IOL in viable singleton gestations. Eligible trials for which raw data were obtained were included and individual participant data meta-analysis was performed. Primary outcomes were vaginal birth, a composite of adverse perinatal outcome (including stillbirth, neonatal death, neonatal seizures, admission to the neonatal intensive care unit, severe respiratory compromise or meconium aspiration syndrome) and a composite of adverse maternal outcome (including admission to the intensive care unit, maternal infection, severe postpartum hemorrhage, maternal death or uterine rupture). The quality of the included RCTs was assessed using the Cochrane Risk of Bias 2 tool and the certainty of evidence was evaluated using the GRADE approach. A two-stage random-effects model was used for meta-analysis according to the intention-to-treat principle and interactions between treatment and baseline characteristics were assessed. RESULTS: Of seven eligible trials, four provided individual participant data for a total of 2815 participants undergoing IOL, of whom 1399 were assigned to Foley catheter and 1416 to oral misoprostol. All four trials provided data for each of the primary outcomes in all 2815 women. Compared with those receiving oral misoprostol, Foley catheter recipients had a slightly decreased chance of vaginal birth (risk ratio (RR), 0.95 (95% CI, 0.91-0.99); I2 , 2.0%; moderate-certainty evidence). A trend towards a lower rate of composite adverse perinatal outcome was found in women undergoing IOL using a Foley catheter compared with oral misoprostol (RR, 0.71 (95% CI, 0.48-1.05); I2 , 14.9%; low-certainty evidence). Composite adverse maternal outcome did not differ between the groups (RR, 1.00 (95% CI, 0.97-1.03); I2 , 0%; moderate-certainty evidence). Meta-analyses of effect modifications did not show significant interactions between intervention and parity or gestational age for any of the primary outcomes. CONCLUSIONS: For women undergoing IOL, Foley catheter is less effective than oral misoprostol, as it was associated with fewer vaginal births. However, while we found no significant difference in maternal safety, Foley catheter induction may reduce adverse perinatal outcomes. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.