To evaluate antenatal risk factors associated with failed induction of labor among obese women to develop a predictive model for induction of labor outcome.
We conducted a population-based cohort study of all obese (body mass index higher than 30.0) women with singleton live births who underwent attempted induction of labor between 37 and 44 weeks of gestation in the United States from 2012 to 2016 using de-identified U.S live birth records. The primary objective was to build a predictive model for the probability of induction of labor failure using antenatal factors. Multivariable logistic regression estimated the association of these factors on risk of failed induction of labor. We performed k-fold cross-validation for internal validation and then externally validated the model using a separate live birth cohort from 2017 (n=197,982). An online calculator was developed after validation, and calibration was performed. The 10 variables selected for inclusion in the model in order of significance were prior vaginal delivery, prior cesarean delivery, maternal height, age, weight at delivery, parity, gestational weight gain, Medicaid insurance, pregestational diabetes, and chronic hypertension.
Among 19,844,580 live births in the United States between 2012 and 2016, 1,098,981 obese women with singleton pregnancies underwent induction of labor, of which 273,184 (24.9%) were unsuccessful. The receiver operator characteristic curve for the 10 variable model achieved an area under the curve (AUC) of 0.79 (95% CI 0.78–0.79). External validation demonstrated a consistent measure of discrimination, with an AUC curve of 0.77 (95% CI 0.76–0.77).
This model provides valuable estimation as to the cumulative effect of multiple factors on the risk of failed induction of labor among obese parturients. The predictive model identifies women at increased or decreased risk (ie, greater than 75% vs less than 20%) for cesarean delivery. This risk calculator may be a useful tool for practitioners in the counseling, triaging, risk stratifying, and delivery planning for obese women before attempted induction of labor.