Predictive factors of induction delivery failure

Background The induction of delivery is a topic widely studied. The literature shows discordant results, probably due to the heterogeneity of populations, variables and outcomes studied. The results of our study agree with the literature about previous deliveries and Bishop score, but not regarding maternal age and fetal weight. The objective of this study is to verify predictors of vaginal delivery in a specific and more homogeneous population of prolonged pregnancies induced with prostaglandins PGE2. Methods We conducted a retrospective cross-sectional study with analytic component. The population was made up of 145 women hospitalized only for ‘‘induction of labor in post-term pregnancy’’ after the 41st week treated with the vaginal device Propess (prostaglandin PGE2). The ‘‘outcome’’ studied was the type of delivery at the end of the induction: vaginal or cesarean. The maternal variables analyzed were: age, weight, height, BMI, BMI percentage increase due to the gestational weight gain, previous deliveries, previous curettage of the uterine cavity, and Bishop score at the beginning of the induction; while the fetal variables were: gestational age, AFI and weight at birth. A descriptive analysis of the population, a monovariate and a multivariate logistic regression was carried. Results 80.7% of the population had a vaginal delivery after the induction. Four significant covariates were included into the final model: age >35 years and the fetal weight at the birth >3500 g resulted very strong risk factors for failed induction (respectively OR 4.20, p=0.006 and OR 3.63, p = 0.013); while previous deliveries and a high Bishop score resulted as protective factors towards delivery induction failure (respec- tively OR 0.16, p = 0.028 and OR 0.62, p = 0.034). Conclusions Our results agree with the literature concerning previous deliveries and Bishop score. However, not all previous studies found results similar to ours regarding maternal age and fetal weight. This could be explained by the peculiarity of our population. Key messages Risk factors for the induction delivery failure are: maternal age >35 years and the newborn weight >3500 g; while previous deliveries and an high Bishop score are protective factors.