(808) Prediction Model for Intrapartum Cesarean Delivery in Pregnancies Complicated by Sonographic Small for Gestational Age

To identify risk factors and develop a predictive model for intrapartum cesarean delivery (CD) in women carrying small for gestational age (SGA) fetuses.

Study Design:

This retrospective cohort study included singleton pregnancies complicated by SGA defined as an estimated fetal weight < 10th percentile at ≥36 weeks’ gestation, delivered between 2013–2024 at a single tertiary center. Exclusion criteria were elective or prior CD and non-viable fetuses. Only CDs performed during labor due to maternal or fetal indications were included. Maternal characteristics, ultrasound findings (including estimated fetal weight [EFW], abdominal circumference [AC] and Doppler), and labor variables were compared between women who delivered vaginally and those who underwent intrapartum CD. Univariate and multivariable logistic regression identified independent predictors, and a predictive model was developed. Model performance was assessed using a receiver operating characteristic (ROC) curve.

Results:

1. A total of 2,035 women met the inclusion criteria, of whom 62 (8.0%) underwent intrapartum CD. Among intrapartum CDs, the most common indication was non-reassuring fetal heart rate (73.0%).


2. Independent risk factors for intrapartum CD included induction of labor (OR 5.87, 95% CI 2.94–11.70), nulliparity (OR 5.50, 95% CI 2.62–11.54), preeclampsia (OR 3.54, 95% CI 1.41–8.93), maternal age >35 years (OR 2.91, 95% CI 1.64–5.16), gestational age between 36-37 weeks (OR 2.81, 95% CI 1.26–6.25),


3. Epidural anesthesia (OR 0.25, 95% CI 0.14–0.45) was found to be protective for intrapartum CD


4. For each percentile increase in fetal abdominal circumference (AC) beyond the 1^st percentile, the risk of intrapartum CD decreased (OR 0.62, 95% CI 0.39–0.99, p=0.049).


5. The predictive model demonstrated good performance with an AUC of 0.792 (95% CI 0.752–0.831; p< 0.001). A cutoff score of 6.5 yielded sensitivity of 74% and specificity of 67%.