VBAC: Vaginal Birth After Caesarean

What VBAC means, and how likely it is

VBAC stands for vaginal birth after caesarean. The alternative is an elective (planned) repeat caesarean section, or ERCS. The RCOG's headline figures: “after one caesarean section, about three out of four women with a straightforward pregnancy who go into labour naturally give birth vaginally”, and if you have had a vaginal birth either before or after your caesarean, “about 8–9 out of 10 women can have another vaginal birth”.

Ireland's HSE gives the same figure — after one caesarean, about 3 in 4 mothers have a vaginal birth — and adds a number for a harder situation: after two caesareans, most births are by caesarean, but if you go into labour naturally “you have about a 7 in 10 chance of a vaginal birth”. In the US, ACOG uses the term TOLAC (trial of labor after cesarean) for the attempt, and VBAC for a successful outcome.

The RCOG's framing is worth holding onto: “If you are fit and healthy, both VBAC and ERCS are safe choices with very small risks.” This is a preference-sensitive decision, not a test you pass. The NHS's own summary is that “most women who have had a caesarean section can safely have a vaginal delivery for their next baby”.

What makes success more likely

The RCOG names three factors: a previous vaginal birth, particularly a previous successful VBAC; labour starting naturally; and a booking BMI under 30. The HSE lists the mirror image — a vaginal birth is less likely if you have never had one, if labour needs to be induced, if labour does not progress, or if your BMI was over 30 at booking. NICE agrees that women with both a previous caesarean and a previous vaginal birth “have an increased likelihood of having a vaginal birth”.

The risks, with numbers

Uterine rupture

This is the risk everyone means when they ask if VBAC is safe. The RCOG: the scar on your uterus “may separate and/or tear (rupture). This can occur in 1 in 200 women. This risk increases by 2 to 3 times if your labour is induced.” For a planned repeat caesarean, the RCOG puts the rupture risk at 1 in 1000. NICE states the principle without a number: for women who have had up to and including four caesarean births, “the risk of fever, bladder injuries and surgical injuries does not vary with planned mode of birth, but… the risk of uterine rupture is higher for planned vaginal birth.”

Ending up with an emergency caesarean anyway

The RCOG says this happens in 25 out of 100 women planning a VBAC — “only slightly higher than if you were labouring for the first time, when the chance of an emergency caesarean section is 20 in 100”. The HSE gives the same 1 in 4.

Other risks

The RCOG lists a slightly higher chance of needing a blood transfusion than with a planned repeat caesarean; a possible assisted birth with ventouse or forceps; and the possibility of a third- or fourth-degree tear. Serious risk to the baby, such as brain injury or stillbirth, is “higher than for a planned caesarean section but is the same as if you were labouring for the first time” — the RCOG quantifies the rare serious risks avoided by ERCS as 2 in 1000.

And the risks of choosing a repeat caesarean

These are real too, and they compound. A repeat caesarean “usually takes longer than the first operation because of scar tissue”, which can make it more difficult and can result in damage to bowel or bladder. There is wound infection, possible transfusion, a higher risk of blood clots, a longer recovery, and no driving for about six weeks. Crucially, the RCOG warns that “more scar tissue occurs with each caesarean section”, increasing the chance of placenta accreta — which can cause heavy bleeding and may require a hysterectomy. If you want more children, that matters.

Where guidance genuinely differs by country

Eligibility is described differently by different bodies, and this is not a translation quirk.

• RCOG (UK): VBAC “is not advisable” if you have had three or more previous caesarean deliveries, if your uterus has ruptured in a previous labour, if your previous caesarean was “classical” (an incision involving the upper part of the uterus), or if you have other complications requiring a planned caesarean. With more than one previous caesarean, it asks for “a detailed discussion with a senior obstetrician”.
• NICE (UK): frames advice around women who have had “up to and including 4 caesarean births”, and requires electronic fetal monitoring and care in a unit with immediate access to caesarean birth and on-site blood transfusion.
• HSE (Ireland): will not recommend vaginal birth after a previous rupture, a high or classical incision, or three or more previous caesareans.
• ACOG (US): emphasises the uterine incision type — low transverse carries “the least chance of future rupture”, low vertical more, high vertical or classical the highest — and adds an access issue the UK bodies do not: “VBAC should take place in a hospital that can manage situations that threaten the life of the woman or her fetus. Some hospitals may not offer VBAC because hospital staff do not feel they can provide this type of emergency care.” In the US, whether VBAC is available to you can depend on your hospital.

ACOG also notes that you “cannot tell what kind of cut was made in the uterus by looking at the scar on the skin” — the records from your previous birth are what settle it.

What labour looks like if you plan a VBAC

You will be advised to give birth in hospital so an emergency caesarean can be carried out if needed (RCOG), and to contact the hospital as soon as you think labour has started or your waters break. Once contractions are regular, continuous monitoring of your baby's heartbeat is advised, because “changes in the heartbeat pattern can be an early sign of problems with your previous caesarean scar”. Pain relief options including an epidural remain available.

If labour has not started by 41 completed weeks, the RCOG says your obstetrician will discuss options: continue waiting, induction — which increases the risk of scar rupture and lowers the chance of a successful VBAC — or a repeat caesarean. NICE says induction after a previous caesarean requires close monitoring with immediate access to caesarean birth.

If you have a planned repeat caesarean but go into labour first, tell your team; the RCOG says an emergency caesarean is likely to be offered, unless labour is very advanced and a vaginal birth is safer.

When to call

Contact your maternity unit immediately during a VBAC labour if you have constant abdominal pain between contractions, pain over your old scar, vaginal bleeding, or you feel something is wrong; scar problems are what continuous monitoring exists to catch. The RCOG advises calling as soon as you think labour has started or your waters break rather than waiting at home. Ask for your birth-options discussion at an antenatal visit “ideally before 28 weeks”, and ask for the operation notes from your previous caesarean if nobody has told you what type of incision you have.