What Is a VBAC? Risks, Benefits, and Who Qualifies

A VBAC is a vaginal birth after cesarean, meaning a person who previously delivered by cesarean section goes on to deliver vaginally in a later pregnancy. The term applies to the outcome, not the attempt: the attempt itself is called a trial of labor after cesarean, or TOLAC. Roughly three out of four people who attempt TOLAC achieve a vaginal delivery, though individual odds vary widely depending on the reason for the prior cesarean, body characteristics, and obstetric history. The distinction between attempting labor and actually delivering vaginally matters, because the risks and benefits look different depending on whether the trial succeeds or fails.

TOLAC Versus VBAC

These two terms get used interchangeably in everyday conversation, but they describe different things. TOLAC is the decision to go into labor rather than schedule a repeat cesarean. VBAC is the result when that labor ends in a vaginal delivery. A failed TOLAC means labor was attempted but a cesarean was performed anyway, often urgently. This distinction shapes the whole conversation about safety: successful VBAC carries fewer complications than a planned repeat cesarean in many respects, while a failed TOLAC tends to carry the highest complication rates of any scenario.¹

How Often TOLAC Succeeds

Large studies consistently show VBAC rates in the range of 60 to 85 percent among those who attempt labor, with the exact figure depending heavily on the population studied and which predictive factors are present. A U.S.-based analysis of nearly 12,000 people found that about 74 percent achieved VBAC.² A Jordanian validation study reported even higher rates, around 83 percent.³ An Indian cohort showed a more modest 55 percent success rate, reflecting differences in patient selection and clinical practice.⁴

Several factors predict who will have a successful vaginal delivery. The strongest positive predictor is having had a vaginal delivery before, especially one that occurred after the cesarean. Being taller, younger, and at a lower pre-pregnancy weight all improve the odds. Conversely, if your prior cesarean was performed because labor stalled (what clinicians call arrest of dilation or descent), your chances are lower. Chronic hypertension requiring medication also lowers the probability.²

Online prediction calculators exist that try to estimate your individual likelihood of VBAC. These tools use factors like age, height, weight, and reason for prior cesarean to generate a probability score. They perform reasonably well in the populations where they were developed, but their accuracy drops when applied to different clinical settings. In one validation study, people with a predicted success probability above 75 percent actually delivered vaginally about 69 percent of the time, while those with a predicted probability around 50 percent still succeeded about 43 percent of the time.⁴ These calculators are useful conversation starters, not crystal balls.

Benefits of a Successful VBAC

When TOLAC results in a vaginal delivery, the advantages over a scheduled repeat cesarean are substantial. Vaginal delivery avoids major abdominal surgery, which means a shorter hospital stay, less blood loss, lower risk of surgical infection, and a faster return to normal activity. One study found that postpartum hemorrhage and prolonged hospitalization were both significantly less common in the TOLAC group than in the repeat cesarean group.⁵

Quality-of-life assessments tell a consistent story. People who delivered vaginally after a prior cesarean reported better physical functioning, stronger emotional well-being, and higher overall satisfaction compared with those who had another surgical delivery.⁶ Breastfeeding outcomes also differ: people who had a repeat cesarean were roughly twice as likely to never initiate breastfeeding compared with those who achieved VBAC, even after adjusting for other factors.⁷

A less obvious benefit involves future pregnancies. Every additional cesarean increases the risk of serious complications like abnormal placental attachment, where the placenta grows into the uterine wall. One study found that roughly half of cases of this dangerous condition following a primary cesarean were considered potentially preventable, meaning the first cesarean may not have been necessary in the first place.⁸ Avoiding a repeat cesarean when safe to do so helps reduce this cumulative surgical risk.

The Cost Picture

VBAC is consistently cheaper than elective repeat cesarean. A historical cost analysis found that the total cost for mother and baby averaged about $5,950 for repeat cesarean versus roughly $4,860 for attempted vaginal delivery.⁹ A European modeling study across four countries found that VBAC was the more cost-effective strategy in every country analyzed, both over a six-week postpartum window and over a lifetime horizon.¹⁰ The savings come from shorter hospital stays, fewer surgical complications, and less use of intensive-care resources.

Risks of Attempting Labor After a Cesarean

The headline risk of TOLAC is uterine rupture, where the scar from the prior cesarean tears open during labor. This is uncommon but serious. A meta-analysis comparing TOLAC with elective repeat cesarean found that TOLAC roughly doubled the odds of uterine rupture.¹¹ In absolute terms, the rate remains low. Among people who have had a previous vaginal delivery, the rupture rate during TOLAC was about 0.2 percent, while those without prior vaginal delivery experienced rupture about 1.1 percent of the time.¹² Having delivered vaginally before is the single strongest protective factor against rupture.

The same meta-analysis found that babies born through TOLAC were more likely to have low five-minute Apgar scores compared to those born by planned repeat cesarean. However, no significant differences emerged in rates of hysterectomy, blood transfusion, postpartum infection, postpartum hemorrhage, or neonatal intensive care admission between the two groups.¹¹ A large U.S. analysis also challenged the assumption that repeat cesarean is safer for newborns: it found that neonatal mortality was actually slightly higher with repeat cesarean than with VBAC.¹³

The picture shifts dramatically when TOLAC fails. A failed trial of labor, meaning one that ends in an unplanned cesarean, carries the worst outcomes of any delivery scenario. One retrospective study found that failed TOLAC was associated with a nearly five-fold increase in uterine rupture risk and a striking nineteen-fold increase in emergency hysterectomy compared with successful VBAC.¹⁴ This is why the prediction of success matters so much: the better your chances of completing a vaginal delivery, the safer TOLAC is overall.

Who Qualifies for TOLAC

The most important factor is the type of uterine incision from the prior cesarean. A low transverse incision, the most common type, is considered safe for a subsequent trial of labor. Low vertical incisions and even unknown incision types are also generally acceptable. What is not safe is a classical (high vertical) incision, which cuts into the thicker, more muscular upper part of the uterus. The rupture risk with a classical scar is substantially higher, and TOLAC is considered contraindicated in those cases.¹⁵ An expert review has confirmed that both spontaneous and induced TOLAC should be offered to most people with one prior low transverse, low vertical, or unknown incision type.¹⁶

The skin incision, by the way, does not tell you what happened inside. Many people with a vertical skin scar still have a low transverse uterine incision. The operative report from the prior surgery is the only reliable way to know, and if it cannot be found, the incision is classified as unknown rather than automatically disqualifying.

An important wrinkle involves cesareans performed very early in pregnancy. When a cesarean is done before the lower uterine segment has fully thinned out (roughly before 28 weeks), the incision may behave more like a classical cut even if it was described as low transverse. One study found that people whose prior cesarean was performed at a very early gestational age had a rupture rate of about 1.8 percent in the next pregnancy, compared with 0.4 percent for those whose prior cesarean was done at term.¹⁷ This does not necessarily rule out TOLAC, but it does warrant closer counseling.

Special Scenarios

People sometimes assume that carrying twins, having a large baby, or having had two prior cesareans automatically disqualifies them from TOLAC. The evidence is more nuanced than that.

Twin pregnancies where the first baby is head-down have been shown to achieve VBAC at rates comparable to singleton pregnancies in some studies, though the data is limited and the scar rupture rate may be slightly elevated.¹⁸ A review of the evidence concluded that twin pregnancy does not preclude VBAC and that suspected large babies should not be considered a contraindication either, since success rates above 50 percent are still achieved and uterine rupture rates are not increased.¹⁹

TOLAC after two prior cesareans is a grayer area. A multicenter study found that people who attempted labor after two previous cesareans and failed had higher rates of both maternal and neonatal complications.²⁰ Most guidelines consider two prior low transverse cesareans a reasonable, though not routine, candidate for TOLAC, with the understanding that the conversation about risks and benefits requires more careful weighing.

How Labor Induction Affects the Equation

Inducing labor in someone with a prior cesarean is one of the more anxiety-provoking clinical decisions. The worry is that drugs used to start or strengthen contractions might put excess pressure on the uterine scar. The reality depends heavily on which method is used.

A large population-based study found that overall, induction was associated with about a 1.6-fold increase in the odds of uterine rupture compared with spontaneous labor. But the risk was not distributed evenly across methods. Prostaglandins, a class of medication used to ripen the cervix, carried the highest risk: about 4.2 percent of those induced with prostaglandins experienced uterine rupture, more than double the overall TOLAC rate. Mechanical methods like a cervical balloon catheter, by contrast, showed no statistically significant increase in rupture risk over spontaneous labor.²¹

Oxytocin, used to augment labor, also carries dose-dependent risk. Research shows that keeping the maximum oxytocin dose at or below 20 milliunits per minute maintains a safe rupture risk, while doses above that threshold increased the risk by four-fold or more.²² Another study found that the cervix’s readiness at the start of labor mattered more than whether labor was induced: when oxytocin was started with the cervix already dilated to four centimeters or more, rupture risk was similar to spontaneous labor. The greatest risk appeared when the cervix was less than two centimeters dilated at the start.²³

Monitoring During Labor

Continuous fetal heart rate monitoring is standard practice during TOLAC because changes in the baby’s heart rate are often the earliest warning sign of uterine rupture. The most consistent early indicator is a sudden, sustained drop in heart rate that does not resolve. In a case series examining confirmed ruptures, researchers noted that the signs and symptoms were typically nonspecific, making diagnosis difficult without close monitoring.²⁴ A case-control study found that severe fetal heart rate abnormalities were significantly associated with uterine rupture in the hour before diagnosis, appearing with elevated frequency as early as 40 to 60 minutes before the rupture was identified.²⁵

This is why TOLAC is recommended at hospitals with the capacity to perform an emergency cesarean within about 30 minutes. The requirement for in-house surgical capability is a real barrier for people who deliver at smaller or rural hospitals, and it is one of the main reasons TOLAC access varies so dramatically by geography.

Pain Relief and Epidurals

A longstanding concern was that epidural analgesia might mask the pain of uterine rupture, delaying diagnosis. In practice, fetal heart rate monitoring, not maternal pain, is the primary detection tool, which blunts this argument considerably. A recent study examining epidural use during TOLAC found that epidurals were associated with higher rates of instrumental delivery (forceps or vacuum) and postpartum hemorrhage, as well as a longer second stage of labor and more frequent use of oxytocin to augment contractions. However, there were no significant differences in neonatal outcomes including Apgar scores, birth weight, or perinatal death.²⁶ Most guidelines do not consider an epidural a contraindication to TOLAC, and many providers actually encourage it so that if an emergency cesarean becomes necessary, anesthesia is already in place.

Disparities in VBAC Access

The overall VBAC rate in the United States climbed by nearly 50 percent between 2011 and 2021, rising from about 10 percent to roughly 15 percent of eligible deliveries. But this progress was unevenly distributed. Hispanic individuals saw the largest gains, while Black individuals had the smallest increase and continued to have lower VBAC rates than the overall population.²⁷ Research has found that Black and Latina individuals actually attempt TOLAC at higher rates than White individuals but achieve VBAC at lower rates, pointing to systemic factors beyond personal preference.²⁸

Geography plays a huge role as well. Western states, especially California, saw the sharpest rises in VBAC rates, while parts of the Northeast saw stagnation or even slight declines.²⁷ Significant variation in VBAC rates exists based on sociodemographic and geographic factors, likely reflecting differences in access to VBAC-supportive hospitals and providers rather than differences in patient preference alone.²⁹ If you live in a region where the nearest hospital does not support TOLAC, your choice may be made for you regardless of your medical eligibility.

Making the Decision

Choosing between TOLAC and a scheduled repeat cesarean is genuinely one of the harder decisions in obstetrics because the right answer depends on your personal risk profile, your values, and your hospital’s capabilities. Research on shared decision-making tools has found that structured decision aids meaningfully improve the process. In one study, people who used a patient decision aid were about six times more likely to score well on a knowledge test about their birth options and roughly three times more likely to make what the researchers classified as an informed, patient-centered decision, compared with routine care.³⁰

A separate pilot study of a shared decision-making toolkit, which included a decision aid, counseling guide, and provider scripts, found that most participants felt they gained knowledge, felt more in control of the decision, and perceived their providers as listening to their concerns.³¹ Research out of Taiwan also found that a person’s early preferences about how they want to deliver shape how actively they seek out information and engage with decision-making during pregnancy, which suggests that the conversation about VBAC ideally starts well before the third trimester.³²

If you are considering TOLAC, the questions worth discussing with your provider include: what type of uterine incision you had, whether you have any of the factors that raise or lower your individual success probability, whether your hospital can perform an emergency cesarean quickly if needed, and how many more pregnancies you are planning. The cumulative surgical risk of multiple cesareans is a legitimate consideration that sometimes gets lost in conversations focused narrowly on the upcoming delivery.

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