VBAC Success: Factors That Increase Your Chances

For many women who have had a previous cesarean delivery, a vaginal birth after cesarean (VBAC) is a safe and desirable option. Success rates vary widely—from about 40% to over 90%—depending on individual risk factors.

Factors That Increase VBAC Success

• Prior vaginal birth (either before or after the cesarean)
• The reason for the first cesarean was non-recurring (e.g., breech position, fetal distress)
• Spontaneous labor
• Normal BMI
• Age < 35
• Single fetus in cephalic (head-down) position

Factors That Decrease Success

• No prior vaginal deliveries
• The first cesarean was done for labor arrest or failure to progress
• Induced labor rather than spontaneous labor
• Higher BMI
• Gestational age > 40 weeks

The Main Risk: Uterine Rupture

The most serious risk of VBAC is uterine rupture along the prior cesarean scar. This occurs in roughly 0.5–1% of VBAC attempts with one prior low-transverse cesarean. The risk increases with more cesarean deliveries or a vertical uterine incision.

Using the VBAC Calculator

The validated VBAC success calculator uses maternal age, BMI, prior vaginal deliveries, and the indication for the prior cesarean to estimate the probability of a successful VBAC. It helps inform shared decision-making between the patient and obstetrician.

Estimate your probability with our VBAC success calculator.