Birth After Previous Caesarean Birth
Key Recommendations
- Women with one previous lower-segment caesarean section (LSCS) should be counselled about both planned VBAC and elective repeat caesarean section (ERCS)
- VBAC success rate is approximately 72-75% overall
- Planned VBAC is associated with a uterine rupture risk of 0.2-0.7% (1 in 200)
- Decision should be shared, considering individual risk factors and maternal preference
VBAC Success Factors
Favourable factors (higher success rate)
- Previous vaginal delivery (especially previous VBAC — success rate >85-90%)
- Spontaneous onset of labour
- Favourable cervix (Bishop score >6)
- Previous caesarean for non-recurrent indication (e.g. breech, fetal distress)
- BMI <30
- Age <40
- Interdelivery interval >18-24 months
- Estimated fetal weight <4000g
Unfavourable factors (lower success rate)
- No previous vaginal delivery
- Previous caesarean for failure to progress/dystocia
- BMI >30
- Induced labour
- Gestation >41 weeks
- Short inter-delivery interval (<18 months)
- Macrosomia
Uterine Rupture
- Risk with lower-segment scar: 0.2-0.7% (1 in 200)
- Risk with classical (upper-segment) scar: 2-9% — VBAC contraindicated
- Risk increases with: induction (especially prostaglandins), augmentation, short inter-delivery interval
- Prostaglandin induction increases rupture risk 2-3 fold
- Signs of uterine rupture: abnormal CTG (most common early sign), acute abdominal pain, vaginal bleeding, maternal tachycardia, cessation of contractions, loss of station of presenting part
Contraindications to VBAC
- Previous classical (upper-segment) caesarean incision
- Previous uterine rupture
- Three or more previous caesarean sections (relative contraindication — individual assessment)
- Previous caesarean with T-shaped or inverted-T incision
- Other contraindication to vaginal delivery (e.g. placenta praevia)
Intrapartum Management of VBAC
- Continuous electronic fetal monitoring (CTG) recommended
- IV access recommended
- Deliver in a unit with facilities for immediate caesarean section
- Abnormal CTG is the most reliable early sign of uterine rupture
- Epidural analgesia is not contraindicated and does not mask rupture signs (CTG changes occur first)
- Oxytocin augmentation may be used with caution; prostaglandins should be avoided
- Mechanical cervical ripening (balloon catheter) may be considered as safer alternative to prostaglandins
Elective Repeat Caesarean Section (ERCS)
- Eliminates risk of uterine rupture
- Higher risk of surgical complications with each subsequent caesarean
- Increased risk of placenta praevia and placenta accreta spectrum in future pregnancies
- Recommended timing: 39+0 weeks (balance of fetal maturity vs risk of labour onset)
- Each additional caesarean increases risk of dense adhesions, bladder injury, and placenta accreta
Important Facts for MRCOG
- Overall VBAC success rate: 72-75%
- Previous vaginal delivery is the strongest predictor of VBAC success
- Uterine rupture risk: 0.2-0.7% with lower-segment scar
- Classical caesarean scar: VBAC contraindicated (rupture risk 2-9%)
- Prostaglandins increase rupture risk — avoid for VBAC induction
- Abnormal CTG is the earliest sign of uterine rupture
- Continuous CTG is recommended during VBAC labour
- Each additional caesarean increases risk of placenta accreta spectrum
Source: RCOG Green-top Guideline No. 45 (2015, 2nd edition (verified current as of 2026-07-17 — rcog.org.uk lists "last reviewed 01 October 2015" with no newer edition; the earlier "reviewed 2020" note could not be substantiated and has been removed))
Read the original on rcog.org.uk
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