Risk factors for failed induction of labor among pregnant women with Class III obesity

Our aim was to identify risk factors for failed induction in morbidly obese patients undergoing the induction of labor at term.

This was a retrospective multicenter study on a cohort of 235 patients with a body mass index greater than 40 kg/m² and giving birth to a singleton in cephalic presentation, who had an induction of labor from 38 weeks of amenorrhea. Scheduled cesareans and spontaneous vaginal deliveries were excluded. Maternal, peri-partum and neonatal characteristics were analyzed according to the delivery route.

In all, 235 patients were included. Of these, 62.5% patients delivered vaginally and 37.5% by cesarean section. The frequency of nulliparity was greater in patients who had a cesarean section (56 [interquartile range, IQR, 38.1] vs 56 [IQR 63.6], P < .001). In multivariate analysis, nulliparity (odds ratio [OR] 2.81, 95% confidence interval [CI] 1.58-4.97], P < .001), low Bishop's score (OR .794, 95% CI .70-.90, P < .001) and weight gain (OR 1.04, 95% CI 1.01-1.08, P = .033) were independent risk factors for failed induction. Umbilical cord pH at birth lower than 7 (0 vs 7 [IQR 8.0], P < .001) and lower than 7.20 (36 [IQR 24.5] vs 35 [IQR 39.8], P = .014) as well as the Apgar at 1 minute (14 [IQR 9.5] vs 17 [IQR 19.3], P = .032) was significantly higher in infants born by cesarean section.

In this cohort, 63% of women with Class III obesity had successful inductions of labor; risk factors for failed induction include nulliparity and unfavorable Bishop score.