V B A C
Young, prior vaginal delivery, favorable factors
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Evidence-based calculations Used in clinical settings worldwide Regular monitoring recommended
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✅ Ideal VBAC Candidate
Young, prior vaginal delivery, favorable factors
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🏆 Prior Successful VBAC
Previous successful VBAC - excellent prognosis
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⚖️ Moderate Risk Profile
First cesarean for dystocia, no prior vaginal
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⚠️ Higher Risk Profile
Multiple cesareans, older age, obesity
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💉 Labor Induction
VBAC with labor induction for post-dates
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⏱️ Short Inter-delivery
Less than 18 months between deliveries
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👩 Advanced Maternal Age
40+ years old with single cesarean
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🎯 Favorable Cervix
Already dilated and effaced at admission
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Demographics
Obstetric History
Current Pregnancy
Additional Factors
For informational purposes only — not medical advice. Consult a healthcare professional before acting on results.
🏥 Health Facts
— WHO
— CDC
What is VBAC (Vaginal Birth After Cesarean)?
VBAC (Vaginal Birth After Cesarean) refers to successfully delivering vaginally after a previous cesarean section. TOLAC (Trial of Labor After Cesarean) is the medical term for attempting a vaginal birth after cesarean. Success rates average 60-80% overall, but vary significantly based on individual factors, making personalized risk assessment essential for informed decision-making between TOLAC and planned repeat cesarean.
Benefits of VBAC
- • Shorter hospital stay (2-3 days vs 4-5)
- • Faster recovery (weeks vs months)
- • Lower infection risk
- • Avoids major abdominal surgery
- • Easier subsequent pregnancies
Risks to Consider
- • Uterine rupture (~0.5-1%)
- • Emergency cesarean if unsuccessful
- • Neonatal complications (rare)
- • Requires 24/7 surgical capability
- • Continuous monitoring needed
Success Rates
- • Overall average: 60-80%
- • Prior vaginal: 85-90%
- • Prior VBAC: 90%+
- • No prior vaginal: 55-65%
- • Prior dystocia: 50-60%
How Does VBAC Success Prediction Work?
The Grobman Prediction Model
Our calculator uses the MFMU (Maternal-Fetal Medicine Units Network) Grobman prediction model, validated on over 11,000 TOLAC attempts. This evidence-based approach considers multiple factors that research has shown to significantly impact VBAC success rates.
Most Important Factors
- 1. Prior vaginal delivery history
- 2. Indication for prior cesarean
- 3. Labor onset type (spontaneous vs induced)
- 4. BMI and maternal age
- 5. Cervical status at admission
Model Validation
- • Validated on 11,000+ TOLAC attempts
- • Published in peer-reviewed journals
- • Used by ACOG for clinical guidance
- • Accounts for modifiable factors
Key Success Factors Summary
| Factor | Impact on Success | Notes |
| Prior vaginal delivery | +15-25% | Most important positive factor |
| Prior successful VBAC | +10-12% | Best predictor of success |
| Spontaneous labor onset | +5-10% | Better than induction |
| Non-recurring indication | +5-10% | Breech, placenta previa |
| BMI over 30 | -5-15% | Dose-response relationship |
| Prior cesarean for dystocia | -10-15% | May indicate pelvis limitations |
| Labor induction | -8-10% | Also increases rupture risk |
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