Comparison of the Effectiveness of Body Mass Index and Abdominal Subcutaneous Fat Thickness in Predicting the Success of Oxytocin-Induced Labor and Cumulative Oxytocin Requirement in Obese Pregnant Women

Purpose To compare body mass index (BMI) and abdominal subcutaneous fat thickness (ASFT) in predicting the success of oxytocin-induced labor and cumulative oxytocin requirement in term pregnancies. Methods We performed a prospective cohort study of 193 term singleton gravidas induced with oxytocin at a tertiary center in Turkey. ASFT was measured by standardized ultrasound before infusion. Primary outcomes were cumulative oxytocin dose and delivery mode; secondary outcomes included labor durations. Group comparisons used ANOVA/Kruskal–Wallis with post-hoc tests. Determinants of oxytocin dose and labor duration were analyzed by univariate and stepwise multivariable regression (p<0.05). Results Higher BMI was associated with longer first-stage and total labor (both p<0.001), without a significant difference in oxytocin dose across BMI groups. Increasing ASFT tertiles were associated with longer first-stage and total labor (both p<0.001). In univariate analyses, ASFT (β=1.73, p=0.001) and Bishop score=1 vs 0 (β=1.98, p=0.013) predicted higher oxytocin dose. In multivariable models, ASFT (β=1.59, p=0.002) and Bishop score=1 (β=2.84, p=0.008) independently predicted oxytocin dose (R²=0.09). For total labor duration, the multivariable model identified active-phase duration (β=0.80, p<0.001), BMI (β=11.51, p<0.001), oxytocin dose (β=4.88, p=0.008), amniotomy (β=38.25, p=0.013), and parity (β=-14.56, p=0.002) as significant (R²=0.49). Neonatal Apgar scores were similar across groups. Conclusions Both BMI and ASFT relate to prolonged labor, but ASFT is an independent predictor of cumulative oxytocin requirement, whereas BMI is not. Incorporating ASFT—alongside cervical status—may improve individualized induction planning, particularly in populations with high obesity prevalence. Prospective multicenter studies are warranted.