Risk Calculator to Predict Cesarean Delivery Among Women Undergoing Induction of Labor.

OBJECTIVE: To develop and validate a predictive risk calculator for cesarean delivery among women undergoing induction of labor. METHODS: We performed a population-based cohort study of all women who had singleton live births after undergoing induction of labor from 32 0/7 to 42 6/7 weeks of gestation in the United States from 2012 to 2016. The primary objective was to build a predictive model estimating the probability of cesarean delivery after induction of labor using antenatal factors obtained from de-identified U.S. live-birth records. Multivariable logistic regression estimated the association of these factors on risk of cesarean delivery. K-fold cross validation was performed for internal validation of the model, followed by external validation using a separate live-birth cohort from 2017. A publicly available online calculator was developed after validation and calibration were performed for individual risk assessment. The seven variables selected for inclusion in the model by magnitude of influence were prior vaginal delivery, maternal weight at delivery, maternal height, maternal age, prior cesarean delivery, gestational age at induction, and maternal race. RESULTS: From 2012 to 2016, there were 19,844,580 live births in the United States, of which 4,177,644 women with singleton gestations underwent induction of labor. Among these women, 800,423 (19.2%) delivered by cesarean. The receiver operating characteristic curve for the seven-variable model achieved an area under the curve (AUC) of 0.787 (95% CI 0.786-0.788). External validation demonstrated a consistent measure of discrimination with an AUC of 0.783 (95% CI 0.764-0.802). CONCLUSION: This validated predictive model uses seven variables that were obtainable from the patient's medical record and discriminates between women at increased or decreased risk of cesarean delivery after induction of labor. This risk calculator, found at https://ob.tools/iol-calc, can be used in addition to the Bishop score by health care providers in counseling women who are undergoing an induction of labor and allocating appropriate resources for women at high risk for cesarean delivery.

Predictive Model for Failed Induction of Labor Among Obese Women.

OBJECTIVE: To evaluate antenatal risk factors associated with failed induction of labor among obese women to develop a predictive model for induction of labor outcome. METHODS: 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. RESULTS: 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). CONCLUSION: 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.