VBAC Success Probability Calculator

VBAC Success Probability Calculator Explanation and Clinical Context This calculator provides an estimated probability of successful vaginal birth after cesarean by applying a logistic regression model developed from a large obstetric cohort. The score integrates maternal age body mass index history of prior vaginal delivery indication for previous cesarean and other clinical predictors that influence the likelihood of successful trial of labor. A history of vaginal delivery especially prior successful VBAC is one of the strongest positive predictors.

Maternal age and increasing body mass index tend to reduce probability of success. A previous cesarean due to arrest disorder usually lowers the likelihood of a successful attempt because it may reflect underlying cephalopelvic or labor progression limitations. The model assists clinicians during counseling by quantifying individualized risk and supporting shared decision making.

It guides selection of appropriate candidates for trial of labor contributing to safer perinatal outcomes when combined with comprehensive clinical judgment. The output should never be interpreted in isolation but rather as part of a full obstetric evaluation including maternal comorbidities fetal status and institutional readiness for emergency delivery. Reference Grobman WA et al Obstetrics and Gynecology 2007 109 806 to 812 doi 10.1097 01.AOG.0000259312.36053.02