A risk-based model for unplanned cesarean delivery following induction of labor in term hypertensive nulliparas.

PURPOSE: To develop a practical risk-stratification framework for unplanned cesarean delivery (CD) among term nulliparous individuals with hypertensive disorders of pregnancy (HDP) undergoing induction of labor (IOL).

METHODS

This was a retrospective cohort study at a single tertiary care center (January 2010-March 2025) of nulliparous individuals with singleton gestations diagnosed with HDP undergoing IOL at ≥ 37 + 0 weeks. We excluded multiple gestations, major fetal anomalies, planned CD, or intrauterine fetal death. We included demographic and pregnancy characteristics available prior to induction and evaluated association with unplanned CD. Stepwise backward logistic regression was used to build a model for identifying independent predictors of unplanned CD. Sensitivity, specificity, and likelihood ratios (LR) were calculated.

RESULTS

Among 1,326 eligible individuals, 347 (26.2%) underwent unplanned CD. Independent predictors of CD were age > 35 years (adjusted odds ratio [aOR] 1.97, 95% CI 1.45-2.66), body mass index ≥ 30 kg/m2 (aOR 2.07, 95% CI 1.58-2.70), HDP with severe features (aOR 1.71, 95% CI 1.17-2.49), thrombocytopenia (aOR 2.66, 95% CI 1.17-6.06), and need for cervical ripening (aOR 1.63, 95% CI 1.23-2.16). Cesarean risk increased stepwise with accumulation of risk factors: 28.4% with ≥ 1 factor, 36.7% with ≥ 2, 44.7% with ≥ 3, and 64.7% with ≥ 4. The presence of ≥ 4 factors yielded a positive LR of 5.17 (95% CI 1.92-13.99).

CONCLUSION

In term nulliparous individuals with HDP undergoing induction, approximately one in four require CD. A simple model based on five routinely available pre-induction factors enables individualized counseling and shared decision-making at the bedside.