VAGINAL BIRTH AFTER CAESAREAN (VBAC).
Birth by caesarean section.
Caesarean section is a surgical operation to deliver a baby through
an incision in the uterus. It is a major operation with great potential
benefit, but also with substantial risks for both mother and baby.
(Enkin et. al.) In Australia the caesarean section rate is approximately
18%. In some places it is much higher. For example, in the major public
hospital in the ACT it has varied between 20 and 25% in the last few
years. Approximately half of these births are elective caesareans
(ie. planned caesareans performed before labour commences. A caesarean
performed during labour is an emergency caesarean). The World Health
Organisation recommends a caesarean rate of no more than 10-15 %.
Available data suggest that there is minimal improvement in outcomes
with a rate above 7%.
Reasons for caesarean section.
Caesareans are performed for a number of reasons. Some of these reasons,
such as placenta praevia (where the placenta is attached across the
cervix), prolapsed cord or transverse lie during labour, are potentially
lifesaving. However, many caesareans are performed for failure to
progress in labour (at the rate decreed by the attending doctor),
cephalo-pelvic disproportion (CPD, baby perceived too big for pelvis)
and possible fetal distress. These indications are very difficult
to diagnose and it is often unclear later whether the caesarean was
really necessary. On the basis of available evidence, having had one
or more previous caesareans is not, by itself, an indication for an
elective caesarean. The large variations in the percentage of births
by caesarean section in the practices of different maternal health
care providers indicates that there is no clear agreement on what
conditions necessitate a caesarean. Enkin, et. al. state that it suggests
that other factors, such as socio-economic status of the woman, the
influence of malpractice litigation, women's expectations, financial
considerations, and convenience, may sometimes be more important than
obstetrical factors in determining the decision to operate.
Effect of caesarean section.
A caesarean section is major surgery with all the attendant risks.
It is not safe. The maternal death rate associated with (but not necessarily
attributable to) caesarean section is 4 times greater than in relation
to all types of vaginal birth. Mother and baby morbidity is significantly
higher. There are risks of anaesthetic accident, operative injury,
infection, effects on subsequent fertility and psychological morbidity.
The rate of respiratory distress syndrome in babies after caesareans
is about 4-6 times higher than for vaginal births. This could be due
to the caesarean birth itself or prematurity caused by miscalculation
of dates. A woman's psychological well being is often seriously affected
after a caesarean, causing, in particular, higher incidence of post
natal depression (up to 6 times) and lower breastfeeding rates. Anger,
disappointment, grief over lost experiences and feelings of failure
and violation are common reactions. Family and sexual relationships
can be seriously affected. The post-operative pain and the high incidence
of wound infections means a longer recovery period with physical mobility
affected for months afterwards. And in addition to all that, caesareans
cost the community significantly more than vaginal births. Caesarean
section is not a preferable way to have a baby for most women. For
some, the desire to give birth vaginally is so strong that a caesarean
section causes grief that may take years to resolve. The possibility
of a vaginal birth in the future may be a lifeline at a time of deep
Why plan a VBAC?
Planning a vaginal birth after a previous caesarean (VBAC) has many
benefits. A vaginal birth will result in 86% of planned VBACs (Flamm,
p64). Some studies show an even higher rate of vaginal births. (90%
ICEA Review, p5) A vaginal birth avoids the risks of surgery and anaesthesia
and improves the health outcomes for the woman and her baby. It is
well documented that babies benefit from the stimulation of labour
and birth, particularly with regard to breathing and alertness at
birth. A woman may wish to give birth without intervention. If the
caesarean experience was particularly distressing it may be very important
to avoid a repetition. It is much less likely that a mother will be
separated from her newborn after a vaginal birth and her partner,
support person or other children can be present for the birth. During
a caesarean a support person can only be present if the woman has
regional anaesthesia. With a vaginal birth a woman is more likely
to feel in control and as if she and her baby are the most important
people present. This is empowering and creates a sense of achievement.
A vaginal birth can be a healing process for a woman who has had a
In contrast to these positive benefits, the reasons most commonly
cited for choosing an elective repeat caesarean rather than a VBAC,
are the possibility of uterine rupture, problems in previous labours,
2 or more previous caesareans, convenience, avoiding the discomforts
of labour, avoiding the perceived risk of emergency caesarean after
a long labour, and current indications such as breech or transverse
position, placenta praevia or 2 or more babies.
This is an extremely remote possibility. The risk is between 0.09%
and 0.22% in women with a low transverse uterine scar. (Enkin et.
al., p291). The probability of requiring a caesarean section for emergency
situations such as acute fetal distress, cord prolapse or ante partum
haemorrhage is about 30 times higher. In fact about 75% of the reported
cases of uterine rupture occur in women who have not had previous
uterine surgery. Of the women who do have a scarred uterus and suffer
a uterine rupture up to one third do not rupture along the scar line.
In addition the literature often does not distinguish between a scar
rupture and dehiscence. The latter is a partial separation of the
uterine wall with little or no symptoms and minimal (if any) maternal
or fetal morbidity. The risk of uterine rupture is not significant
enough to warrant choosing elective repeat caesareans. Previous obstetric
history including 2 or more previous caesareans A history of caesarean
birth for CPD, slow labour, being overdue, fetal distress, placenta
praevia, position of the fetus or multiple birth is not a reason for
elective repeat caesarean. Nor is a history of 2 or more caesareans.
There is little or no difference in the morbidity figures for VBACs
after 2 or more caesareans and the vaginal delivery rate is almost
the same as for women with only one previous caesarean. the available
evidence does not suggest that a woman who has had more than one previous
caesarean section should be treated any differently from the woman
who has had only one caesarean section. (Enkin et. al. p288).
Cephalo-pelvic disproportion (CPD).
This indication has been shown repeatedly to be inaccurate as a predictor
of the possibility of future vaginal births. Up to 77% of women with
a previous caesarean for CPD have a later vaginal birth. One third
of them with larger babies. (ICEA Review). X-rays are notoriously
inaccurate as a means of diagnosing CPD. The movement of a woman's
pelvis during labour and the position of the baby are so significant
that an x-ray prior to, or during, pregnancy cannot reliably indicate
the likelihood of vaginal birth.
Breech presentation occurs in about 3-4% of all singleton births.
It should always be remembered that a baby can change position at
any time up until the start of labour. So a caesarean performed for
breech position before labour commences may be an unnecessary caesarean,
even if you consider that a breech position warrants a caesarean.
There are many things that a woman can do to help her baby turn, including
postural exercises, homeopathics, visualisations and external version
(turning the baby manually through the uterine wall. Some practitioners
do not recommend this practice). Even if the baby does not turn, breech
VBAC is still an option with an experienced practitioner.
There are many issues to be examined by a woman expecting twins (or
triplets, etc.). Generally however a multiple birth is not automatically
a reason for caesarean section. The pregnant woman should have access
to accurate information to enable her to make the best choice in her
Enkin et. al. considered a wide range of factors including all the
risks and benefits of each option outlined above to determine the
optimal birth choice after a caesarean. They came to the conclusion
that planned labour proved to be the safer choice.(p287)
Most women do not voluntarily submit themselves and their babies
to the risks of caesarean section. They need as much care and love
as any new mother and baby. And a woman planning a VBAC may need extra
support and understanding as she rebuilds her belief in herself in
preparation for another birth. It is to be hoped that every woman
who is planning a birth after one or more previous caesarean sections
is encouraged and supported to plan a vaginal birth.
A Guide to Effective Care in Pregnancy and Childbirth, Enkin, Keirse,
Renfrew and Neilson, 1995 (2nd Edn)
Birth after Caesarean: The Medical Facts, Dr Bruce L Flamm, 1990 (USA)
Childbirth Choices, Bennett, Etherington and Hewson, 1993 (Aust)
Silent Knife, Nancy Wainer Cohen & Lois J Estner, 1983
So You're Thinking About VBAC.., (pamphlet) ICEA ICEA Review (VBAC),
(pamphlet) ICEA, 1990 (USA)
Vaginal Birth After Caesarean, (pamphlet) M. Brorup Weston, P Simkin
and K Keolker, 1987 (USA)