A VBAC (pronounced “vee-back”) is a vaginal birth after cesarean, meaning you deliver vaginally in a pregnancy that follows a prior C-section. For decades, the standard advice was “once a cesarean, always a cesarean,” but that changed as evidence showed most women with a previous C-section can safely labor again. About 73% of first-time VBAC attempts end in a successful vaginal delivery, and that number climbs above 90% for women who have had a previous successful VBAC.
TOLAC vs. VBAC: Two Different Things
You’ll often see the term TOLAC alongside VBAC, and the distinction matters. TOLAC stands for “trial of labor after cesarean,” which is the process of attempting labor. VBAC is the outcome when that attempt succeeds. Every VBAC starts as a TOLAC, but not every TOLAC ends in a VBAC. Some women who begin labor will need an unplanned repeat cesarean if complications arise or labor stalls. Understanding this distinction helps set realistic expectations: choosing a TOLAC means you’re giving vaginal birth a try, with a backup plan already in place.
Who Is a Good Candidate
The biggest factor is the type of incision on your uterus (not the skin incision, which can look different). A low transverse incision, the most common type, carries the lowest risk and makes you a reasonable candidate. Certain scar types rule out a VBAC entirely. A classical (vertical) incision on the upper part of the uterus, a T-shaped incision, or a history of extensive surgery through the top of the uterus all carry rupture rates of 4 to 9%, which is too high for a safe labor attempt.
Beyond the scar, several personal factors influence your chances. A validated prediction tool uses five key variables: your BMI, age, whether you’ve had a prior vaginal delivery, whether your previous cesarean was due to labor that failed to progress, and whether you have chronic high blood pressure requiring treatment. An earlier version of this tool used race as a variable, but developers replaced it after criticism that it produced systematically lower predicted success rates for Black and Hispanic women.
The single strongest predictor is whether you’ve had a successful VBAC before. Women with at least one prior VBAC have a 93.4% success rate, compared to 73.3% for those attempting it for the first time. Having delivered vaginally before essentially confirms that your pelvis can accommodate a baby, which is why that history carries so much weight. Interestingly, once you’ve had one successful VBAC, additional ones don’t significantly change the odds further. They stay above 90%.
Why Some Women Choose VBAC
A successful VBAC avoids major abdominal surgery and the recovery that comes with it. After a vaginal birth, most women are up and moving within hours. After a cesarean, recovery typically involves weeks of limited activity, pain management, and restrictions on lifting. For women caring for older children at home, this difference can be significant.
The benefits extend beyond a single pregnancy. Each additional cesarean increases the risk of serious complications in future pregnancies, including life-threatening bleeding, the placenta attaching over the cervix (placenta previa), and the placenta growing into or through the uterine wall. These risks compound with each surgery. Women planning larger families stand to gain the most from avoiding repeated cesareans, because each one makes the next pregnancy riskier.
The Main Risk: Uterine Rupture
The primary concern during a TOLAC is uterine rupture, where the scar from a prior cesarean opens during labor. This is uncommon but serious, requiring emergency surgery to protect both the mother and baby. For women with one prior low transverse cesarean, the overall rupture rate is roughly 5 per 1,000, with the range falling between 2 and 9 per 1,000.
How labor starts and progresses affects this risk. Women who go into labor on their own have a rupture rate of about 0.7% and a vaginal delivery success rate of 74.3%. When labor is induced, the rupture rate rises to about 2.2% and the success rate drops to around 60.7%. The use of certain medications to stimulate contractions further increases the risk. Women given synthetic oxytocin during a TOLAC have a rupture rate of 1.4%, compared to 0.5% for those who labor without it.
Not all induction methods carry the same risk. International guidelines recommend mechanical methods like a Foley catheter or breaking the water over hormonal agents for starting labor in women with a prior cesarean. One specific medication, misoprostol, is explicitly advised against because it is associated with a higher uterine rupture rate in scarred uteruses.
What Labor Looks Like During a TOLAC
Labor itself is managed much the same as it would be for any vaginal delivery. Your labor progress is assessed using the same standards as someone without a prior cesarean, because research shows labor patterns are similar in both groups. The second and third stages of labor (pushing and delivering the placenta) also follow the same approach.
The key difference is monitoring. You’ll need continuous observation by an obstetric provider in a facility that can perform an emergency cesarean quickly if needed. This means not all hospitals or birth centers offer TOLAC. The facility needs trained staff, appropriate equipment, and the ability to move to surgery without delay. If you’re considering a VBAC, it’s worth confirming early in your pregnancy that your chosen hospital supports it and has the resources in place.
There is a lower threshold for intervening during a TOLAC than during a typical vaginal delivery. If any signs suggest the uterine scar may be giving way, the care team will move quickly to a cesarean. Signs can include sudden severe pain between contractions, changes in the baby’s heart rate, or unexpected bleeding.
How Success Rates Stack Up
Your individual odds depend heavily on your history. In a study of nearly 3,000 eligible deliveries, success rates climbed steadily with each prior VBAC:
- No prior VBAC: 73.2% success rate
- 1 prior VBAC: 92.3%
- 2 prior VBACs: 94.7%
- 3 prior VBACs: 94.0%
- 4 or more prior VBACs: 97.0%
A history of even one prior VBAC was associated with a five-fold higher likelihood of success. For first-time VBAC candidates, the roughly 73% success rate still means nearly three out of four women deliver vaginally, though one in four will end up with a cesarean after laboring. That’s an important number to weigh. An unplanned cesarean after hours of labor carries slightly more risk than a scheduled repeat cesarean, so the decision involves balancing the potential benefits of vaginal delivery against the possibility of an emergency surgical birth.
Your care provider can help you assess where you fall on the spectrum by reviewing your specific history, the reason for your prior cesarean, your current pregnancy, and the factors that feed into validated prediction models. That conversation, ideally started well before your due date, is the foundation for making a decision that fits your goals and your medical reality.