Multivariate Analysis of Determinants and Development of a Predictive Algorithm for Successful Labor Induction in Nulliparous Women

Background The present investigation aims to develop an innovative predictive nomogram capable of predicting successful labor induction in nulliparous women, thereby elucidating critical determinants influencing such success and estimating the probability of successful induction in term singleton pregnancies. Methods This retrospective cohort analysis included 1,000 term pregnant nulliparas who underwent labor induction in the Ultrasound Department of the National Traditional Chinese Medicine Hospital in Xiangxi Tujia and Miao Autonomous Prefecture between January 2017 and December 2024. We conducted univariate and multivariate logistic regression analyses after comparing various clinical parameters. The outcome variable was defined as the binary success of labor induction, while potential predictors included maternal demographics, obstetric characteristics, cervical conditions (e.g., Bishop score, endocervical impedance [ECI], internal os [IOS], external os [EOS]), duration of oxytocin administration, and presence of a nuchal cord. The model's performance was assessed via receiver operating characteristic (ROC) curve analysis, the concordance index (C-index), a calibration plot, and decision curve analysis (DCA). Results Labor induction was successful in 715 patients (71.5%) and failed in 285 patients (28.5%). Significant differences were observed in the Bishop score and cervical length (CL) between the two groups (P < 0.05). Notably, the ECI, IOS, and EOS were markedly lower in the successful induction group than in the failure group (P < 0.05), whereas heart rate was significantly elevated (P < 0.05). Stepwise selection identified the CL, Bishop score, ECI, and hardness ratio (HR) as significant predictors, which were incorporated into a final logistic regression model. The area under the ROC curve was 0.79 (95% CI: 0.71–0.85), with a corrected C-index of 0.753, indicating satisfactory discrimination and calibration. Conclusion Through comprehensive evaluation, we identified cervical length, the Bishop score, the ECI, and HR as pivotal determinants of successful labor induction. A nomogram incorporating these four factors was constructed to predict the likelihood of successful induction in term singleton nulliparous women. This visual clinical instrument serves as an adjunctive tool for guiding personalized induction strategies based on individual risk profiles.