The great majority of women who fall pregnant plan to give birth naturally. However for a number of reasons many women wind up having their first baby by caesarean section. Many women who give birth by caesarean are extremely disappointed to have done so – even if they understand and accept the reasons for their caesarean.

Such women should consider the option of planning to have their next baby vaginally. We call this approach planning a Vaginal Birth After Caesarean or VBAC for short.

VBAC has been around for almost as long as caesarean sections have. Like a number of aspects of obstetric care, VBAC has been in and out of fashion over the years. For the vast majority of last century the dictum “Once a caesarean, always a caesarean” held true in the USA. By contrast, hospitals under British influence (including those in Australia) have always viewed VBAC as being a valid option for women with a previous caesarean.

The reason for the conservative approach in the USA was the – reasonable – fear that contractions of the uterus might cause the uterus to rupture, with potentially catastrophic consequences for the mother and the baby. This risk was greatest with the now vary rare “up and down” – or classical – incision in the uterus. Caesareans have usually been performed by a low “side to side” – or lower segment – incision for a number of decades.

Perhaps surprisingly VBAC was the subject of very little scientific study over the vast majority of the twentieth century so traditional forms of management held sway on both sides of the Atlantic Ocean.

The 1980′s – a time of change

Following the rise of feminism in the 1970′s the women’s movement challenged many norms including the absolute “always a caesarean” approach. A number of scientific studies began to be published in the 1980′s that suggested that many women with a previous caesarean could give birth vaginally safely. These studies suggested that women who had previously undergone a lower segment caesarean had a more than 70 percent chance of giving birth vaginally if they attempted labour. The risk of the uterus rupturing in labour was comparatively low – 0.5 to 1 percent (one in 100 to 200 women) –  with adverse consequences for either the mother or the baby being extremely rare.

With the benefit of hindsight a number of these studies were perhaps over optimistic mainly because they included women who had previously given birth vaginally as well as having had a caesarean. We now know that women who have had both a vaginal birth and a caesarean have a higher success rate and lower complications when they have a VBAC compared to women who have only ever given birth by caesarean.

Anyway these studies led to a resurgence in the popularity of VBAC in the USA (remembering that VBAC was always in fashion in the UK and Australia) such that by 1990 VBAC was the standard of care for women with a previous caesarean on both sides of the Atlantic. When I trained in New Zealand and the UK in the 1990′s we assumed women with a previous caesarean would have a VBAC and women were strongly discouraged from choosing an elective caesarean when they had previously given birth by caesarean. Indeed in the early 1990′s VBAC was compulsory in the USA – health funds refused to pay for elective caesareans because VBAC was perceived to be better and – most importantly – cheaper – than elective caesareans.

By the way this widespread adoption of VBAC in the USA during the1990′s had another benefit – it reined in the USA’s escalating caesarean section rate such that the USA national caesarean rate fell from around 25 percent to around 20 percent by the mid 1990′s (In fact it seems the only way to reduce national caesarean rates is to increase VBAC rates.)

However in the mid 1990′s two things happened that changed the attitudes of obstetricians (and health funds) in the USA and, to a lesser extent, the UK and Australia. These were:

  1. A number of babies were born in extremely poor condition following VBAC attempts with expensive lawsuits following, and
  2. Studies began to appear in the scientific literature that suggested that the success rate for VBAC was not as high as had been previously thought (60 percent rather than over 70 percent), that mothers who did not succeed to give birth vaginally (i.e. required emergency caesareans) suffered a high rate of complications, and babies did – albeit rarely – come to serious harm from VBAC attempts.

These studies confirmed that the risk of the uterus rupturing during a VBAC attempt was indeed between 0.5 and 1 percent and that when such ruptures occurred there was an increased risk of the baby dying or suffering brain damage. On the other hand the overall risk of the baby coming to serious harm from a VBAC attempt was low in absolute terms – perhaps one in 1,000. Then again (and I am sorry about this) an elective caesarean was demonstrated to be significantly safer than VBAC for the babies of women with previous caesareans.

Just to further complicate matters a number of other factors appeared in studies published in the early part of this century. These findings included:

  • That inducing or speeding up labour with drugs such as prostaglandins or oxytocin significantly increased the risk of the uterus rupturing during a VBAC attempt (from up to one percent to as much as two to five percent, depending upon the circumstances).
  • That VBAC attempts were most safely conducted in larger hospitals because of their infrastructure; in particular their ability to safely conduct an emergency caesarean section within 30 minutes of identifying a possible uterine rupture.

So where do we stand from a scientific point of view?

I can try to summarise our current understanding of the scientific literature regarding VBAC for women who have given birth once before, by caesarean section (i.e. They have not given birth vaginally), in the following list:

  • The success rate (i.e. the chances of giving birth vaginally) for VBAC when labour starts naturally is approximately 60 percent. Induction of labour is almost certainly associated with a lower chance of a vaginal birth – possibly as low as 40 percent. (Remember of course that a number of vaginal births occur with the assistance of the ventouse or forceps.)
  • The risk of the uterus rupturing during spontaneous labour in a VBAC attempt is around 0.5 percent (or one in 200). This risk is increased to one percent with augmentation (speeding up) of slow labour with oxytocin and more than two percent with induction of labour using prostaglandins.
  • The risk of a baby coming to serious harm (i.e. dying or suffering a serious brain injury) during a VBAC attempt is low in absolute terms (between one in six hundred and one in one thousand) but significantly higher than with the alternative – the risk of a baby coming to serious harm during an elective caesarean is less than one in ten thousand. Then again (and I am sorry about all of these “then again”s) the risk of a baby coming to serious harm from a VBAC attempt is little different from the risk of harm occurring to a baby during a woman’s first labour and birth – after all simply being born carries some risk for all babies.
  • A completely natural birth poses significantly lower risks for women than undergoing a caesarean and this holds true for women who have a previous caesarean section. Even the most ardent advocate of caesarean childbirth could not make a credible case that a caesarean is safer for the mother than a completely natural birth. But a more complex issue is the risks involved when a planned VBAC does not succeed – i.e. when an emergency caesarean becomes necessary. An emergency caesarean – particularly when it occurs during a VBAC attempt – has significantly higher risks for the mother than an elective caesarean performed without labour.
  • Limited scientific data suggests that women can give birth vaginally after two caesareans although it is likely that they face a higher risk of the uterus rupturing than women with one pervious caesarean. (Again much of the scientific literature on this topic includes women who have also given birth vaginally and these women have better outcomes than those that have not previously given birth vaginally.)

OK so who should NOT attempt to give birth vaginally?

I believe attempting a VBAC is not such a good idea for women who:

  • Have undergone two or more previous caesareans
  • Have previously undergone surgery that may have weakened the uterus, including some (but not all) operations involving removal of fibroids
  • Have previously had a classical caesarean section or any other caesarean involving a cut into the upper part of the uterus
  • Have a condition that absolutely precludes a vaginal birth such as a placenta praevia (where the placenta is blocking the birth canal)
  • Have any concerns about their baby’s welfare such as the baby being small for gestational age or having low amniotic fluid
  • Have significant medical or obstetric complications
  • Have a Body Mass Index (BMI) over 30. Bigger women have lower VBAC success rates than lean women and emergency caesareans can have additional complications for them when compare with planned elective caesareans

Who should plan to attempt a VBAC?

Women should plan to have a VBAC if they wish to try for a vaginal birth (it isn’t compulsory) and:

  • They have previously undergone an uncomplicated lower segment caesarean
  • They have one baby and it is in the head first position
  • Their baby is normally grown – i.e. not too big (likely to weigh more than 4 kilograms at birth) and not too small
  • They have no significant complications of pregnancy, particularly with respect to their baby’s welfare
  • They do not need induction of labour

Is anything different about labour when we are attempting a VBAC?

Not really.

Seriously!?

OK, well, a little…

You can – largely at least – plan for your labour to take place just as you wish it to. You can do Calm Birth, Hypnobirthing, Juju or whatever approach you wish for your labour. You can labour in water and you can give birth upright (or upside down if that is your wish). I would advise against actually giving birth in water (as opposed to laboring in it) but we can discuss this further if you feel strongly about water birth.

You can use whatever you want for pain relief, including an epidural if that is your preference or the pain becomes too much. Some caregivers believe that epidurals can either:

a)    Diminish the likelihood of a natural birth with VBAC and / or

b)    Mask the signs (ie.pain) of the uterus rupturing.

There is no scientific evidence to support these views and a great many successful VBACs have occurred with epidurals for pain relief.

However I advise that your baby’s heart beat be continuously monitored throughout the active part of your labour with a VBAC. This is because the most reliable sign of a possible rupture of the uterus is abnormalities in the baby’s heart beat pattern (although to be fair this is the best of a bad bunch). It is important that you understand that we now have wireless (and even underwater!) fetal heart monitors so this imposition should not interfere with your mobility during labour or your birth experience.

Those of you who know me will not be surprised to read that I assume any abnormality in your baby’s heart rate during a VBAC attempt is a rupture of the uterus until proven otherwise so I usually advise a caesarean straight away if your baby’s heart rate pattern becomes abnormal (when there is no scar on the uterus we can sometimes take a “wait and see” approach to heart rate abnormalities – at least for a short time). This type of conservative approach of course is why vaginal birth rates are lower for women having a VBAC than for those in other circumstances.

I also recommend that we place a small cannula (plug) in one of your veins just in case of problems during labour. This need not be connected to a drip so – again – your mobility will not be impeded.

Where should a VBAC take place?

Not at home. While I have no major opposition to home birth for women without complications (and whom preferably have given birth vaginally previously) I don’t recommend home VBAC.

I (and most scientific and professional bodies) believe that VBAC labours should take place in hospital delivery units where it is possible to conduct an emergency caesarean within 30 minutes of deciding to do so. The risk of harm coming to babies when the uterus ruptures has been shown to be lower in larger hospitals with operating theatres that are fully staffed 24 / 7.

In Randwick – and with no disrespect to Prince of Wales Private Hospital (POWP) – this hospital is The Royal Hospital for Women. The Royal has its operating theatres fully staffed with nurses, anaesthetists and paediatricians 24 hours per day whereas at POWP we need to call staff in from home in order to conduct a caesarean outside usual office hours. Accordingly I prefer to conduct VBACs at The Royal.

And finally:

Many women – particularly those who have previously experienced a prolonged labour that ended in an emergency caesarean – are happy to have a planned elective caesarean for their next birth (“there’s no way I’m going through that again!”). That of course is a fair and reasonable approach.

Many other women however are bitterly disappointed to have given birth by caesarean (remembering that a significant number of them may not have even experienced labour because of placenta praevia or breech presentations in their previous pregnancy). Such women may wish to go for a VBAC in their next pregnancy.

VBAC is a perfectly reasonable and – with small caveats only – safe approach to birth for women who wish to try labour after a previous caesarean and it is a choice that I fully support.