Prediction of Delivery Mode in Primiparous Women Based on Clinical and Intrapartum Ultrasound Parameters

Objective : To monitor intrapartum ultrasound in primiparous women entering the first stage of labor and construct a model to predict the delivery mode for these women. Materials and Methods: A total of 203 full-term singleton primiparous women admitted to our hospital for vaginal delivery between February 2022 to November 2023 were included. Initially, cervical dilation and fetal presentation were assessed by midwives through vaginal examination. Subsequently, ultrasound monitoring of the labor progress was conducted, with both assessments conducted blindly. Measurements were performed according to the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) guidelines, including abdominal assessment of fetal presentation and transperineal measurements of the angle of progression (AOP), head-perineum distance (HPD),progression distance (PD), and midline angle (MLA). Three measurements were performed for each parameter, and the average values were calculated. The participants were divided into a vaginal delivery group (163 cases) and a cesarean section group (40 cases) based on the delivery outcome. Clinical and ultrasound parameters were analyzed to determine differences between the two groups. Multiple logistic regression analysis was conducted to identify the independent influencing factors, and a nomogram was constructed. The robustness of the model was assessed and its clinical effectiveness was evaluated,which was then externally validated. Results : (1) Maternal height, weight, gestational age, estimated fetal weight (EFW), maternal gestational diabetes, and maternal preeclampsia showed no statistical differences (P > 0.05), whereas epidural analgesia, fetal presentation, AOP, MLA, HPD, and PD exhibited significant differences (P < 0.05). (2) Multiple logistic regression analysis revealed that epidural analgesia, fetal presentation, AOP, and HPD were independent factors influencing vaginal delivery. The constructed nomogram exhibited a sensitivity of 74.2%, a specificity of 77.5%, and an area under the curve (AUC) of 0.808 (95% confidence interval: 0.729-0.886). (3) The nomogram prediction model was externally validated,and the constructed nomogram exhibited a sensitivity of 78.3%, a specificity of 80.0%, and an area under the curve (AUC) of 0.839 (95% confidence interval: 0.717-0.961). Conclusion : Epidural analgesia, fetal presentation, AOP, and HPD were identified as independent factors influencing vaginal delivery in primiparous women. The nomogram model based on clinical and intrapartum ultrasound parameters demonstrated robustness and effectiveness, providing a valuable tool for predicting delivery mode.