Establishment and validation of a prognostic model for premature rupture of membranes and preterm delivery in pregnant women after cervical conization.

Objective: To investigate the risk factors for premature rupture of membranes (PROM) and preterm birth in pregnant women following cervical conization. A nomogram model was developed and validated to predict the occurrence of PROM and preterm birth in this population.

Methods: A total of 100 pregnant women who had undergone cervical conization between January 2014 and December 2023 were included. The participants were divided into two groups: 52 in the PROM group and 48 in the non-PROM group. Additionally, 43 cases were in the preterm birth group, and 57 were in the full-term group. Maternal age, body mass index (BMI) during pregnancy, and the conization method were recorded. A nomogram model was constructed to predict PROM and preterm birth, with the predictive performance evaluated using the area under the ROC curve (AUC), C-index, and decision curve analysis (DCA).

Results: Univariate and multivariate regression analyses identified pre-pregnancy obesity, advanced maternal age, time after conization, and second-trimester cervical length as significant risk factors for PROM and preterm birth. These factors were incorporated into a clinical nomogram. Calibration curves demonstrated excellent internal and external accuracy for the model. The AUC for the nomogram was 0.8746. DCA showed the clinical utility of the model when the threshold probability ranged from 20% to 60%.

Conclusion: Pre-pregnancy obesity, advanced maternal age, time since conization (<12 months), and second-trimester cervical length (<25 mm) were identified as independent risk factors for predicting PROM and preterm birth in pregnant women after cervical conization.