TOLAC stands for Trial of Labor After Cesarean. It refers to the process of attempting a vaginal birth after having a cesarean section (C-section) in a previous pregnancy. If that attempt succeeds, the result is called a VBAC, or vaginal birth after cesarean. The two terms are closely related but describe different things: TOLAC is the attempt, and VBAC is the outcome when it works. Success rates generally fall between 60% and 80%, though individual odds vary based on several personal and medical factors.
How TOLAC Differs From VBAC
These two terms often get used interchangeably, but they represent distinct stages. When you and your provider decide to plan for vaginal delivery after a prior C-section, you are choosing a TOLAC. You go into labor (or are induced) with the goal of delivering vaginally. If labor progresses well and you deliver without needing another C-section, you’ve had a VBAC. If complications arise during labor and a cesarean becomes necessary, the TOLAC was attempted but did not result in a VBAC.
This distinction matters because it shapes the conversation with your provider. Agreeing to a TOLAC means accepting that there’s a meaningful chance you’ll still end up with a cesarean delivery. Roughly 20% to 40% of TOLAC attempts do not result in a vaginal birth.
Who Is a Good Candidate
The strongest candidates for TOLAC are people who had a single prior C-section with a low transverse incision, which is the most common type. This horizontal cut across the lower part of the uterus carries a lower risk of tearing open during a future labor. A prior vaginal delivery, especially a previous VBAC, is one of the best predictors of success.
Several factors make TOLAC less advisable or rule it out entirely:
- Classical (high vertical) uterine incision. This type of cut runs vertically on the upper portion of the uterus and significantly raises the risk of uterine rupture during labor.
- Previous uterine surgery. Operations such as fibroid removal can leave scars that weaken the uterine wall.
- Short interval between pregnancies. Delivering less than 18 months after a prior cesarean is associated with a higher risk of the uterus rupturing at the scar site.
- Two or more prior C-sections. Success rates drop to around 50%, and the risk profile changes enough that many providers approach this cautiously.
- Other health concerns. Conditions that could complicate vaginal delivery, such as placenta previa, may make a planned repeat cesarean the safer choice.
What Predicts Success
Clinicians use prediction models to estimate how likely a TOLAC is to end in a vaginal birth. The Maternal-Fetal Medicine Units Network developed a widely used calculator that weighs factors including maternal age, height, pre-pregnancy weight, whether you’ve had a previous VBAC, and the reason for your original C-section. If the first cesarean was performed because labor stalled (called an arrest disorder), success rates tend to be somewhat lower than if the C-section was done for a non-recurring reason like a breech baby.
At the time of hospital admission, cervical dilation, how thin the cervix has become, and how far the baby has descended all help refine the estimate. A provider might discuss these numbers with you during the third trimester or when you arrive in labor, giving you a personalized picture rather than just the broad 60% to 80% range.
Benefits of a Successful TOLAC
Vaginal delivery after a cesarean avoids major abdominal surgery. Recovery is typically faster, with a shorter hospital stay and less postoperative pain. You can usually resume normal activities sooner compared to recovering from another C-section.
There are also longer-term advantages. Each additional cesarean increases the complexity of future pregnancies because of scar tissue buildup. Successful VBAC has been linked to lower rates of blood clots, postpartum infection, and complications in subsequent pregnancies. A large review of over 200 studies found that maternal mortality was significantly lower with planned TOLAC compared to elective repeat cesarean (about 0.38 versus 1.34 per 10,000 births). For people planning multiple future pregnancies, avoiding repeated abdominal surgeries can be especially meaningful.
Risks to Understand
The primary concern with TOLAC is uterine rupture, where the scar from the previous C-section tears during labor. This is uncommon but serious, potentially requiring emergency surgery and carrying risks for both you and the baby. The risk is highest for those with a short interpregnancy interval or a high vertical scar.
A failed TOLAC, where labor is attempted but a cesarean becomes necessary, can carry more risk than a planned repeat cesarean. That’s because an unplanned surgery during active labor tends to be more urgent and complex. One study found that composite neonatal complications occurred in about 6.7% of failed TOLAC cases, compared to roughly 2% after a successful vaginal delivery. Perinatal mortality is slightly higher with planned TOLAC overall (about 13 per 10,000 births versus 5 per 10,000 with a planned repeat cesarean), though the absolute numbers are very small in both groups.
These risks are why TOLAC is typically recommended at hospitals equipped to perform an emergency cesarean quickly if needed. The availability of surgical and anesthesia teams on short notice is a key part of ensuring safety during the attempt.
What the Experience Looks Like
If you choose TOLAC, your prenatal care in the months leading up to delivery will include conversations about your specific risk factors and the logistics of where you’ll give birth. Your provider will confirm your type of uterine incision (which may require requesting operative records from your prior C-section, since the skin incision doesn’t always match the uterine one).
During labor itself, you’ll be monitored closely. Continuous fetal heart rate monitoring is standard because changes in the baby’s heart rate can be an early warning sign of uterine rupture. Labor may begin on its own or, in some cases, be induced, though induction methods are chosen carefully to avoid overstimulating the uterus.
If labor progresses normally, the delivery itself is no different from any other vaginal birth. If signs of distress develop for you or the baby, the team will move to a cesarean. Many people describe the experience as feeling empowered by having the option to try, even when they understand it might not work out. Knowing the realistic odds beforehand helps set expectations either way.