Predicting the Risk of Emergency Cesarean Delivery in Nulliparous Korean Women at Term

Background: To develop a nomogram for identifying nulliparous women at high risk of unplanned cesarean delivery (CD) during labor at term pregnancy Methods: This retrospective cohort study involves singleton pregnancies delivered between October 2008 and October 2017 at a tertiary center. We included nulliparous women at term conducting a trial of labor. We identified the risk factors for CD during labor based on logistic regression analysis and created a predictive nomogram. We assessed predictive performance with respect to calibration and validation using C-statics and calibration plot. Results: Overall, a total of 3237 nulliparous women met our inclusion criteria and were randomly divided into a training set (n = 1618) and a validation set (n = 1619). The risk due to the five preselected parameters for emergent CD during labor was as follows: advanced maternal age [adjusted odds ratio (aOR), 1.101; 95% confidence interval (CI) 1.058-1.146], higher maternal height [aOR, 0.955; 95% CI 0.928-0.983], increasing BMI [aOR, 1.147; 95% CI 1.098-1.199], fetal head circumference [aOR, 1.116; 95% CI 0.976-1.276], and fetal abdominal circumference [aOR, 1.161; 95% CI 1.055-1.276]. A nomogram was developed to indicate the individual risk of emergency CD during labor, with excellent calibration and discriminative ability, and the C-indices were 0.714 and 0.703 in the training and validation sets, respectively Conclusions: We developed a validated nomogram using five variables to identify nulliparous Asian women at high risk for CD during labor at term pregnancy. This model might be useful for counseling of individual women at risk of CD and to modify the current management protocols.