Women who have had a previous caesarean birth are a higher-risk group for future vaginal births. VBAC is the usual term for Vaginal Birth After Caesarean, and is pronounced 'Vee-back'. These pages were initially written after requests from women considering home VBAC, but they are also relevant for those planning hospital births.
Note: If you are looking for information on home VBAC, you may want to jump straight to Is Home VBAC an option?
Many women who have previously had a caesarean will be offered the option of an elective repeat caesarean section, rather than a 'trial of labour' (which means an attempt at vaginal birth). However, overall VBAC appears to be safer for mother and baby than elective caesarean.
'A Guide to Effective Care in Pregnancy and Childbirth', a famous text for obstetricians and midwives which assesses the 'gold standard' of evidence-based care, has an expanded section on vaginal birth after caesarean in its new edition. It says:
"Overall, attempted vaginal birth for women with a single previous low transverse cesarean section is associated with a lower risk of complications for both mother and baby than routine repeat cesarean section."
"The morbidity (illness) associated with successful vaginal birth is about one-fifth that of elective cesarean. Failed trials of labour, with subsequent cesarean section, involve almost twice the morbidity of elective section, but the lower morbidity in the 80% of women who successfully give birth vaginally means that overall women who opt for a planned vaginal birth after cesarean suffer only half the morbidity of women who undergo an elective section." 
Babies born by elective caesarean are at increased risk of breathing difficulties, while mothers have a longer recovery from the major abdominal surgery of a caesarean, compared to a vaginal birth. Certain complications are more likely with a caesarean - haemorrhage, for example, or emergency hysterectomy.
The risk of a mother who has one past caesarean ending up with a hysterectomy after a subsequent caesarean was 1 in 90, according to a recent study from the UK . However, for women having a vaginal birth who did not have a past caesarean, the rate was only 1 in 5,189. The rate for women having a VBAC is not given, but is likely to be between these two figures.
The risk of some complications, such as hysterectomy or placental problems (see below) rises with every past caesarean a woman has. This means that the balance of risks and benefits of elective repeat caesarean versus attempting VBAC will change, according to whether the mother hopes to have more children after her current pregnancy. It has been said that each caesarean section shifts some of the risks from that baby, on to all the mother's future children. If it is important to a woman that she can have more children, then VBAC should be seriously considered.
Now let's consider the risks of a mother dying during a caesarean. A study of mothes in the Netherlands between 1983 and 1992 found that the death rate from caesareans was seven times that from vaginal birth. A similar study of mothers in Sweden during the 1970s found that caesarean sections were twelve times more likely to end in death of the mother . These are the first two studies which I found on a Medline search, and are not picked for any particular reason. More references will follow in time.
For more information about the risks of caesarean sections, see the Association of Radical Midwives archives (www.radmid.demon.co.uk/csrisks.htm)
A mother who has had a past caesarean is at higher risk of uterine rupture than a mother whose uterus has not been operated on. This means that the old caesarean scar might not stand the strain of labour, and could tear open. The risk of this happening with a standard, modern caesarean scar is around 1 in 200. For more details, see VBAC and Uterine Rupture - there are various factors which increase your risk of uterine rupture, such as having your labour induced or augmented with drugs, or decrease your risk, such as having previously had one VBAC.
Uterine rupture can also occur before labour starts, so planning a repeat caesarean is no guarantee of safety. The sad fact is that, once you have had a caesarean, your risks are increased, whatever route your future births take.
If the uterus ruptures, the baby must be born as soon as possible by caesarean section, and any delay carries risks that the baby will be brain-damaged or will die. The mother could also lose a lot of blood.
But a mother planning VBAC is not just a walking uterus threatening rupture. There are many other complications of pregnancy and birth that are far more likely to happen to any mother, than uterine rupture is to happen to her. Around 75% of VBAC candidates do give birth vaginally, but the remaining 25% who have repeat caesareans will do so for many reasons - rarely for uterine rupture. A VBAC mother is at least five times more likely to need an immediate caesarean for other acute conditions (eg antepartum haemorrhage, severel fetal distress) than she is for uterine rupture [1a]. In a typical planned hospital birth, she is around 50 times more likely to have another caesarean for any other reason, than she is for uterine rupture.
Two placental problems are significantly more likely when a woman has had a previous caesarean. They are placenta praevia, and placenta accreta.
'Placenta praevia' means that the placenta has implanted over the cervix, making vaginal birth impossible or very dangerous. Placenta praevia is easily diagnosed by ultrasound scan, and elective caesarean is the only solution for a complete praevia, where the placenta is actually over the os (the top of the cervix, which is the exit from the womb). Confusion often occurs with definitions, though - a woman whose placenta is merely close to the cervix, but not actually over it, may be told that she has placenta praevia. As the lower segment of the uterus stretches in later pregnancy, the placenta may move away from the os so that vaginal birth and home birth is still a reasonable option.
Placenta Accreta occurs when the placenta attaches deeply to the uterine wall, and does not detach normally in the third stage of labour. It can cause severe blood loss as the uterus is unable to clamp down while the placenta remains in it. The placenta usually has to be surgically removed afterwards. The rate of placenta accreta is much higher in women with a prior caesarean, than otherwise. It is most likely to be found in combination with placenta praevia. If the placenta is nor implanted over the cervix, then the rate of severe placenta accreta is very low. However, when severe placenta accreta occurs, it can life-threatening, whether it was diagnosed beforehand or not, and whether you planned a vaginal birth or a repeat caesarean. The only advantage to having a repeat caesarean is that you are already in the operating theatre when the emergency happens.
Placenta accreta can be diagnosed by MRI (magnetic resonance imaging) scans, but this check would normally only be used when a woman has already been diagnosed as having placenta praevia. If it is confirmed that you do not have placenta praevia, then your caregiver is unlikely to be worried about the possibility of placenta accreta.
Some doctors and midwives worry that the chance of placenta accreta is increased if the placenta is implanted over the scar from a past caesarean, and the uterus was closed with a single layer of stitches rather than a double layer . If the location of your placenta is checked with a scan and confirmed to be clear of the scar, then presumably you should be able to rule out this worry as well. If the scan suggests that the placenta is implanted on the front (anterior) wall of the uterus, rather than the back (posterior) wall or top (fundus), as is more common, then you might want to discuss this with your midwife. Your risk of placenta accreta is still extremely low if you do not have placenta praevia, but it is a factor you might wish to consider.
Some women would rather plan a repeat caesarean, than face the worry that an attempt at vaginal birth would end in caesarean anyway. Your chances of a successful vaginal birth vary according to various factors, such as the reasons for your past caesarean, and the number of past caesareans you have had. These and other factors are discussed on the 'Chances of a VBAC' page.
If you decide to choose an elective repeat caesarean, rather than attempting VBAC, you may find that the experience is less upsetting than your unplanned caesarean. Planning a Good Caesarean is a collection of suggestions from mothers and midwives on the Association of Radical Midwives website which may help you.
Is Home VBAC an option?
Chances of a VBAC is relevant to women considering VBAC, either at home or in hospital. It summarises studies which have looked at how many women who attempt VBACs do give birth vaginally, and how many end up with another caesarean. The stage of dilation you reached with the last labour, the reason for the caesarean, and your past obstetric history all affect your chances.
VBA2C - vaginal birth after two or more caesareans
VBAC and Uterine Rupture explains what uterine rupture is, and how likely it is to happen.
Warning signs of uterine rupture, and what might happen if it occurs.
VBAC and induction or acceleration of labour
VBAC when you are expecting twins
Independent Midwives in the UK are often experienced in attending VBACs at home and in hospital. This page looks at the advantages of hiring them and gives contact details.
The National Childbirth Trust can put you in touch with specialist VBAC supporters. Call the NCT enquiry line on 0870 444 8707 and ask for the contacts for VBAC and Caesarean Support.
ICAN - International Caesarean Awareness Network
Discussions on VBAC from the UK's Association of Radical Midwives
VBAC.com - a new US site which promises a "woman-centered, evidence based, resource".
VBAC information for parents and midwives, in US Midwife Archives at Gentlebirth.org
VBAC articles at Childbirth.org
 Effective Care in Pregnancy and Childbirth, eds. Enkin, Keirse,Renfrew & Neilsen, 3rd Edition (published 2000, OUP), p360
[1a] Chapter 38, section 6. The probability of requiring an emergency CS for other acute conditions (fetal distress, cord prolapse or antepartum haemorrhage) in any woman giving birth is approximately 2.7%
 Placenta accreta in Kuwait: does a discrepancy exist between fundal and praevia accreta?
Makhseed M; Moussa MA
Eur J Obstet Gynecol Reprod Biol 1999 Oct;86(2):159-633
The rate of accreta in patients with placenta praevia was 880 per 100,000 placenta praevia, compared to a rate of 5 accreta per 100,000 placenta implanting in the upper uterine segment.
 A New VBAC Concern, by Ina May Gaskin - Birth Gazette, 2000
 15 out of 53 mothers, 'Home Births: report of the 1994 confidential enquiry by the National Birthday Trust Fund', p69, and see also p216.
 Gould, D et al, 'emergency obstetric hysterectomy - an increasing incidence', Journ. Obset. Gynaecol. 1999 vol 19 p580-583
 Maternal mortality after cesarean section in The Netherlands.
AUTHORS: Schuitemaker N; van Roosmalen J; Dekker G; van Dongen P; van Geijn H; Gravenhorst JB
SOURCE: Acta Obstet Gynecol Scand 1997 Apr;76(4):332-4.
 Cesarean section and maternal mortality in Sweden 1973-1979.
AUTHORS: Moldin P; Hokegard KH; Nielsen TF
SOURCE: Acta Obstet Gynecol Scand 1984;63(1):7-11.
CITATION IDS: PMID: 6720260 UI: 84199115
Last updated: 22 August 2001
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