Analysis of the outcomes and factors influencing vaginal trial labor in primiparas at term.

Purpose: To explore the outcomes and factors influencing vaginal trial labor in primiparas with term singleton fetuses.

Methods: A retrospective analysis of 9174 first-time mothers who opted for a vaginal trial of labor at Peking University First Hospital from October 2019 to September 2022 was performed. The primary outcomes included the outcome of the trial of labor and influencing factors.

Results: Of the total population, the success rate of attempted vaginal delivery was 74.3% (6818/9174). Logistic regression analysis revealed that increasing maternal age (OR = 1.054; 95% CI = 1.239-2.316; p < 0.001), gestational weight gain (OR = 1.033; 95% CI = 1.022-1.045; p < 0.001), neonatal weight (OR = 1.971; 95% CI = 1.724-2.253; p < 0.001), prepregnancy body mass index (BMI) ≥ 24 kg/m² (OR = 1.605; 95% CI = 1.411-1.825; p < 0.001), prenatal BMI ≥ 24 kg/m² (OR = 1.326; 95% CI = 1.137-1.546; p < 0.001), and induced labor (OR = 2.434; 95% CI = 2.187-2.708; p < 0.001) increased the risk of failed vaginal delivery attempts, and labor analgesia reduced the risk of failed vaginal delivery attempts (OR = 0.356; 95% CI = 0.320-0.397; p < 0.001). However, the use of assisted reproductive technology had no significant effect on the outcome of attempted vaginal delivery (p = 0.137). According to the partial regression coefficient, the area under the ROC curve was 0.710 (95% CI = 0.698-0.723), and the model passed the Hosmer-Lemeshow test and had good discrimination and calibration (χ² = 12.833, p = 0.118). The postpartum hemorrhage (PPH) rate and overall neonatal asphyxia rate differed significantly between women who had different outcomes of vaginal trial labor.

Conclusions: There are many factors affecting the occurrence of abnormal delivery in primiparas. These independent factors can be used for prenatal evaluation.