Vaginal Birth following Caesarean Section-VBAC
Vaginal Birth following Caesarean Section (VBAC)
Patient Information
Obstetrics & Gynaecology Department
- Author ID: PE
- Leaflet ref: Obs 028
- Version: 9
- Leaflet title: Vaginal Birth following Caesarean Section (VBAC)
- Last Review: October 2024
- Expiry Date: October 2026
Introduction
VBAC stands for Vaginal Birth after Caesarean. It is the term used when a woman gives birth vaginally having had a caesarean delivery in the past. Vaginal birth includes birth assisted by forceps or ventouse (suction).
More than one in five women (20%) in the UK currently give birth by caesarean delivery (a surgical operation where a cut is made in your abdomen and your baby is delivered through that cut). Many women have more than one caesarean delivery.
If you have had one or more caesarean deliveries, you may be considering how to give birth next time. Whether you have a vaginal birth or a caesarean delivery in a future pregnancy, there are risks and benefits for both you and your baby. Overall both are safe choices with only very small risks.
In considering your choices, you and your obstetrician will need to consider your medical and obstetric details. Some key information here is:
- The reason you had the caesarean delivery and what happened – was it an emergency?
- The type of cut that was made in your uterus (womb).
- How you felt about your previous birth. Do you have any concerns?
- Whether your current pregnancy is straightforward or are there complications?
You and your obstetrician or midwife will consider your chance of a successful vaginal birth, your personal wishes and future fertility plans when deciding about vaginal birth or caesarean delivery.
What we know to answer your queries
Research shows that VBAC is safe for most women and that repeat caesareans may offer no advantage for the mother or her baby. However, mothers are not always aware of these facts and maternal request is a common reason for delivering a baby by caesarean section. Your midwife and doctor will be able to discuss the safety of VBAC with you.
The reason for the previous caesarean section is an important factor and if this is not clear to you, it would be appropriate to ask about this. Once you have this information, you may want to consider the following:
When is VBAC likely to be successful?
- Overall, about three out of four women (75%) with a straightforward pregnancy give birth vaginally following one caesarean delivery.
- After elective caesarean section for breech presentation you are more likely to achieve successful vaginal birth than if the caesarean section was for other reasons.
- If you have had two previous uncomplicated caesarean deliveries, the chance of a successful vaginal birth is slightly less than this between (70 – 75%).
- If you have had a vaginal birth, either before or after your caesarean delivery, the chance of a successful vaginal birth is about nine out of 10 women (90%).
- There is an increased chance of a successful vaginal birth if:
- Your labour starts naturally. Induction of labour using drugs (prostaglandins) has been shown to increase the risk of caesarean section. A large baby does not mean that VBAC cannot be considered.
- Your waters break on their own during labour – nature designs this to happen towards the end of the first stage of labour.
Remember though, that induction of labour or breaking the waters may have to be suggested because the midwife or obstetrician caring for you thinks there is a clinical need.
When is VBAC less likely to be successful?
A number of factors (risk factors) make the chance of a successful vaginal birth less likely:
- If you never had a vaginal birth.
- If you need to be induced.
- If you are overweight – Body Mass Index (BMI) over 30.
When all of these factors are present, four in 10 women (40%) have a vaginal birth.
Other factors which make VBAC success slightly less likely are:
- If you have not gone into labour by 41 weeks.
- You have a big baby (more than 4 kilograms or 8 pounds 13 ounces).
- You do not have an epidural.
- You had a previous caesarean birth before 37 weeks.
- You are still in early labour when you come into hospital (cervical dilation less than 4 centimetres).
- It is less than two years since your last caesarean delivery.
- You are older in age.
What are the advantages of a successful VBAC?
The advantages of a successful VBAC include:
- a shorter stay in hospital
- less abdominal pain after birth
- no restriction on driving a car
- a greater chance of an uncomplicated normal birth in future pregnancies
- a reduced chance of needing a blood transfusion
- a reduced chance of developing a thrombosis (blood clot in the legs).
- A reduced chance of the after birth being abnormally attached to the womb in future pregnancies
- A reduced chance of having scar tissue in the pelvis
What are the risks from VBAC?
They include:
- Emergency Caesarean delivery
There is a chance you will need to have an emergency caesarean delivery during your labour. This happens in 25 out of 100 women (25%). This is only slightly higher than it is in your first pregnancy when the chance of an emergency caesarean delivery is 20 in 100 women (20%). The usual reasons for an emergency caesarean delivery are slow labour or if there is a concern for the wellbeing of the baby.
- Blood transfusion
Women with unsuccessful VBAC (emergency caesarean section) have a 3 in 100 (3%) chance of needing a blood transfusion compared with 1 in 100 for those who successfully deliver vaginally or have an elective caesarean section.
- Infection in the uterus
In an unsuccessful VBAC there is an 8% chance of developing an infection in the uterus compared with 1% for those who have successful VBAC or choose a repeat planned caesarean delivery.
- Scar weakening or scar rupture
There is a small chance that the scar on your womb will weaken and open. This is called scar dehiscence (separation). If you go into labour naturally, the chance of this happening is one in 200 (0.5%). If you are induced with prostaglandins, the chance of this happening is 1.5 in 100 (1.5%). The chance of this happening is not affected by the length of time from your previous caesarean section.
- Risks to your baby
The risk of your baby dying or being brain damaged in labour is very small 2 in 1,000 women (0.2%). This is no higher than if you were labouring for the first time, but it is higher than if you have an elective repeat caesarean delivery 1 in 1,000 (0.1%). However, this must be balanced against the risks to you if you have a caesarean delivery (see below).
Can I be induced?
Induction of labour increases the risk of scar separation by two to three times compared to labour which starts spontaneously but it is still rare only, occurring in one to two women in 100. The chance of successful VBAC is lower: 67 in 100 (67%). Because of these risks the decision to induce labour should be discussed with you by a consultant obstetrician. It may be that even if you have planned a vaginal birth, you will decide that if your pregnancy is overdue, you will have a caesarean section rather than induction of labour.
As part of the induction process, you can receive a mechanical method of induction, called Dilapan which does not require hormones and does not increase the risk of caesarean scar rupture. Your doctor will discuss this with you if it is needed.
What happens when I go into labour when I am planning VBAC?
You will be advised to deliver in hospital so that an emergency caesarean delivery can be carried out if necessary. Contact the hospital as soon as you think you have gone into labour or if your waters break.
Once you are in labour, your baby’s heartbeat will be monitored continuously to pick up any sign of the baby being in distress, as this may mean that you would need another caesarean section.
You should be able to have an epidural if you choose and this can then be used as the anaesthetic if you need a caesarean delivery as an emergency.
What happens if I have an elective caesarean planned and I go into labour?
Telephone the hospital to let them know what is happening. It is likely that an emergency caesarean will be performed once labour is confirmed. If labour is very advanced, or if the labour is preterm (your pregnancy is less than 37 weeks), then VBAC may be more suitable. Your obstetrician will discuss this with you.
When is VBAC not advisable?
There are very few occasions when VBAC is not advisable and repeat caesarean delivery is a safer choice. These are:
- If you have had three or more previous caesarean deliveries.
- If the uterus has ruptured during labour.
- If you had a high uterine incision involving the whole length of the uterus (classical caesarean section).
Home birth
The current national recommendation is that women with a uterine scar need to give birth to their baby in a setting where the baby can be delivered within 30 minutes if an emergency arises.
So whilst having a home birth is not completely out of the question, you should consider this recommendation before making a decision.
Your choices for mode delivery after previous caesarean section
Vaginal Birth after (previous) Caesarean Section (VBAC) | Elective Repeat Caesarean Section |
What are the Benefits? | |
Benefit to you
Benefits to baby
| Benefits to you
Benefit to your baby
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What are the Risks? | |
Risks to you
Risks to your baby
| Risks to you
Risks to your baby
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