Vaginal birth after cesarean (VBAC) occurs when a woman who previously gave birth via cesarean (C-section) has a vaginal birth with a later pregnancy. VBAC reached its peak of popularity in 1996: in that year, nearly 30 percent of U.S. women with a history of cesarean birth gave birth vaginally with a later pregnancy.
Trends over time
After 1996, however, the VBAC rate fell dramatically, and by 2018 just over 13 percent of women achieved a VBAC while the cesarean rate remained about 32 percent--nearly one in three U.S. births.
In an effort to reduce the number of C-sections, the American College of Obstetricians and Gynecologists (ACOG) reexamined its VBAC guidelines. In a 2019 statement, ACOG described VBAC as "appropriate for many women [who have had a prior cesarean delivery]. And according to the National Institute of Child Health and Human Development (NIH), research shows that among appropriate candidates, about 75% of VBAC attempts are successful.
However, one researcher estimated in 2018 that half of U.S. hospitals don’t offer VBAC as an option. Fear of litigation has been cited as the reason.
In its 2019 document Vaginal Birth After Cesarean Delivery, ACOG reiterated the benefits—as well as the risks—of VBAC.
Benefits and risks
VBAC may offer several health advantages over another C-section: lower risk of hemorrhage and infection, likelihood of a shorter hospital stay and a faster recovery, and reduction in risk of negative outcomes related to multiple cesareans.
However, a failed trial of labor after cesarean (TOLAC)—an attempted VBAC that ends in a repeat cesarean—brings many potential complications, including maternal hemorrhage, infection, operative injury, thromboembolism, and hysterectomy. In rare cases, complications may result in death.
Clearly the decision about whether to attempt a VBAC must be made with care. A woman’s medical history, her current health status, and her plans for the future all need to factor into the decision on how to handle the delivery of her baby.
Factors in a woman’s medical history that increase the odds of a successful VBAC include the following:
- Low transverse (horizontal) incision for the C-section (the type of incision made in the uterus can’t be determined by the orientation of the scar on the skin but must be checked for in medical records)
- Prior vaginal delivery (having given birth vaginally with a previous pregnancy)
These factors decrease a woman’s odds of a successful VBAC:
- Previous vertical incision (a zipper-like cut) in the uterus, especially if the vertical incision was high
- A first cesarean that was a result of “arrested labor” or “failure to progress” rather than a result of the baby’s position (breech)
And these factors indicate that a woman should not attempt a VBAC:
- Prior uterine rupture (separation at the site of a previous incision)
- Conditions that contraindicate vaginal delivery (for example, placenta previa, in which the placenta extends over the uterine opening)
- More than two previous C-sections
Current health status
The following factors go along with less chance of success with VBAC:
- greater maternal age
- high blood pressure, diabetes, or obesity
- gestational age greater than 40 weeks
- baby with a birth weight greater than 4,000 grams or 9 pounds
- labor that is induced or supplemented with medication, such as Misoprostol or Pitocin
- short interval between pregnancies
Plans for the future
If a woman is planning to have more children in the future, she may want to consider VBAC to help avoid problems associated with having multiple C-sections. Such problems include scar tissue or adhesions that could lead to bowel or bladder injury or cause problems with the placenta.
A shared decision
Decisions regarding VBAC should be made on an individual basis, with physicians and pregnant women working together to weigh the risks of VBAC against those of a repeat cesarean.
For women who choose to try for a VBAC, ACOG warns against planning a home birth. According to ACOG, a VBAC should be attempted only in a medical facility with staff available to step in if needed should uterine rupture or other unpredictable complications occur.