Vaginal birth after caesarean

# Overview
Vaginal birth after caesarean (VBAC) refers to the practice of delivering a baby vaginally (naturally) after a previous baby has been delivered through caesarean section (surgically).  .  A caesarian section leaves a scar in the wall of the uterus.  This scar is weaker than the normal uterine wall, so if the woman goes in labor in a subsequent pregnancy there is a higher than normal risk of a ruptured uterus, a catastrophic complication.  Because of this risk an attempt at normal vaginal delivery was for most of the 20th century considered unacceptably risky.  This opinion was challenged by many studies showing that many women with previous caesaran sections did have successful vaginal deliveries.  In the 1980s and 1990s there was a strong movement to encourage attempts at vaginal delivery after caesarean section.  For a while some regulatory bodies in the US monitored the percentage of those women with previous caesareans who were offered vaginal delivery, using this number as a measure of the quality of obstetrical care.  Studies in the 1990s confirmed that vaginal delivery after previous caesaran section was indeed much riskier than average.  The American College of Obstetrics and Gynecology issued guidelines which identify VBAC as a high-risk delivery requiring the availabilty of an anesthesiologist, an obstetrician, and on operating room on standby  (Int J Gyn Obs; 1999; vol 66, p197). In the 1990s the rate at which VBAC was tried fell from 26% to 13%.
According to the American Pregnancy Association, 90% of women who have undergone cesarean deliveries are candidates for VBAC.  From 60-80% of women opting for VBAC will successfully give birth vaginally.

# Drawbacks and benefits
The decision to have a trial of VBAC is made by the mother with the advice of her obstetrician.  The decision is guided by an assessment of the known risk factors for complications.  In general, an attempt at VBAC is safe if there are no other identified risk factors.
Risks of cesarean section include a higher chance of re-hospitalization after birth, infertility, and uterine rupture in the next birth.  The risk of uterine rupture in a VBAC is 0.2% to 1.5%.  Because of the risks involved, many health insurance companies will not support VBAC.  Today only about 10% of eligible women in the United States try VBAC.
It is also difficult to find a hospital or doctor willing to do a VBAC because of ACOG's insistence on stringent safety guidelines. The doctor of a VBAC patient is required to be at the hospital throughout the entire labor, and an anesthesiologist needs to be immediately available.
The risk of infection doubles if vaginal delivery is attempted but results in another cesarean..  All complications of cesarean section are more likely and more severe if it is done as an emergency after a failed attempt at vaginal delivery rather than as a planned operation.
The benefits of a VBAC are as follows. There is less medical risk to the mother and the baby than a repeat cesarean. There is less blood loss and therefore fewer transfusions are needed. There is less risk of infection for the mother and the infant. It is less costly to have a VBAC and the recovery time is shorter.
A VBAC can also often help the mother mentally. Women are often depressed or angry about the first cesarean and see a VBAC as righting a past wrong. The mother and infant have more time for immediate bonding, and nursing is often easier.

# Eligibility
There are several common methods of determining eligibility.  Some common factors include:
- If the previous caesarean(s) involved a low transverse incision there is less risk of uterine rupture that if there was a low vertical incision, classical incision, T-shaped, inverted T-shaped or J-shaped incision.
- A previous successful vaginal delivery (before or after the caesarean section) increases the chances of a successful VBAC.
- The reason for the previous caesarean section should not be present in the current pregnancy.
- The more caesarean sections that a woman has had, the less likely she will be eligible for VBAC.
- The presence of twins will decrease the likelihood of VBAC.  Some doctors will still allow VBAC if the twins are positioned properly for birth.
- VBAC may be ruled out if there are other medical complications (such as diabetes), if the mother is over 40, if she is past her due date, if the baby is in the wrong position, etc.
For women planning to have many children, VBAC may be a better option because repeat caesarean sections get more complicated each time.

# History
VBAC is not uncommon today. The medical practice until the late 1970s was "once a caesarean, always a caesarean" but a consumer-driven movement supporting VBAC changed the medical practice. Rates of VBAC rose in the 80s and early 90s, they have fallen since.