TOLAC Versus VBAC: What is the Difference?

Shannon M. Clark, MD
August 26, 2022
TOLAC Versus VBAC: What is the Difference?

*Updated 10/2022

Is a vaginal birth after a cesarean delivery (VBAC) possible?

If you have asked yourself this question, you are not alone! There are many reasons that a cesarean delivery (CD) is performed, but with a subsequent pregnancy, a person may choose to have a vaginal delivery. Some reasons one may want to have a trial of labor after cesarean delivery (TOLAC) include being able to hold their baby immediately after delivery, avoid the major surgery and recovery time required to heal from a repeat CD, or to simply experience a vaginal birth.

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"VBAC" is the delivery of a baby vaginally after a prior CD

The process of attempting a VBAC is called a trial of labor after a cesarean or TOLAC. While a TOLAC may be considered after previous CD, it is critical that a thorough review of risks and benefits be done with your obstetrical care provider. The decision making should incorporate a person’s preferences and desires, as well as the circumstances surrounding their previous CD. If after counseling you decline a TOLAC, then you will undergo a repeat cesarean delivery (RCD).

Many people are good candidates for TOLAC!

Most persons are candidates if they have had one previous low transverse CD. That means the scar on your uterus (not the skin) is horizontal in the lower part of your uterus. Such a person can be and should be counseled and offered a TOLAC if there are no other medical complications at play; candidacy is also based on individualized assessment. Even if a patient is not the best candidate, but presents to labor and delivery in active labor, clinical judgment may be used to determine the best route for delivery.

The risks and benefits should be discussed between patient and provider. Decisions surrounding TOLAC should not only focus on the outcomes of that pregnancy, but should also include a discussion of future pregnancies. The decision to undergo TOLAC or RCD, following counseling, should be made by the patient in consultation with their provider.

The VBAC calculator can also be used to help guide the decision on whether or not to proceed with TOLAC. Evidence suggests that those with at least a 60–70% likelihood of achieving a VBAC who attempt TOLAC experience the same or less maternal morbidity than those who have an elective RCD.

Types of uterine incisions

...but not everyone is a candidate for TOLAC! Here is the most recent ACOG guidance:



Macrosomia (birth weight >4,000g or 4,500g)
Gestational Age > 40 Weeks
  • Decreased VBAC rates in those who attempt TOLAC
  • Data on rupture conflicting
  • Gestational age > 40 alone does not mean someone cannot have a TOLAC
Previous (documented) Low-Vertical incision
  • Studies show a similar rate of VBAC success
  • No consistent evidence of increased risk of uterine rupture or other complications
  • Provider and patient may elect TOLAC
Unknown Prior Uterine Incision
  • Previous case series reported VBAC success and rupture rates similar to known low transverse scars
  • If one previous cesarean and unknown scar, patient may be a candidate for TOLAC if no clinical suspicion for classical incision
Twin Gestation
  • Consistent evidence shows that outcomes are similar to TOLAC with singleton gestations
  • Patients twin gestation and one previous low transverse scar incision are candidates for TOLAC
  • BMI alone is not an absolute contraindication to TOLAC, but should be considered an additional risk factor that may lower chance of VBAC
  • Obese patients have increased risk related to CD
More than one prior CD
  • Two previous low transverse CDs should be counseled and offered TOLAC
  • Data limited on >2 previous CDs


ACOG Vaginal Birth After Cesarean Delivery (VBAC) FAQs

ACOG Practice Bulletin No. 205: Vaginal Birth After Cesarean Delivery

Risks and Benefits of TOLAC, VBAC, and RCD

At this point, you might have some thoughts on whether or not you're a candidate for or desire to undergo a TOLAC. Now you might want to know the risks and benefits of each.

Risks of having multiple cesarean deliveries:

  • Placenta accreta and previa
  • Operative injury: cystotomy, bowel injury, ureteral injury
  • Ileus
  • Need for postoperative ventilation and intensive care unit admission
  • Hysterectomy
  • Blood transfusion requiring 4 or more units
  • Duration of operative time and hospital stay
  • Maternal hemorrhage
  • Thromboembolism
  • Infection

Benefits of VBAC:

  • Avoidance of major abdominal surgery
  • Lower rates of hemorrhage, blood clots, and infection
  • Shorter recovery time
  • Decreased risk of maternal consequences related to having multiple cesarean deliveries (eg, hysterectomy, bowel or bladder injury, blood transfusion, infection, and abnormal placentation such as placenta previa and placenta accreta)

Risks of TOLAC:

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Cesarean section

Here are some more resources for you!

ACOG Vaginal Birth After Cesarean Delivery (VBAC) FAQs

ACOG Practice Bulletin No. 205: Vaginal Birth After Cesarean Delivery

Repeat Cesareans and Failed TOLACs: It’s OK to Feel Like You Missed Out

Maternal morbidity associated with multiple repeat cesarean deliveries

MFMU Network Calculator for VBAC

Prediction of vaginal birth after cesarean in term gestations: A calculator without race and ethnicity

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Shannon M. Clark, MD

Shannon M. Clark, MD

Shannon M. Clark, MD, MMS is a double board certified ObGyn and Maternal-Fetal Medicine Specialist, and founder of Babies After 35. In her roles as a clinician, educator and researcher at UTMB-Galveston, she focuses on the care of people with maternal and/or fetal complications of pregnancy. Dr. Clark has taken a special interest in pregnancy after the age of 35, which according to age alone, is considered a high-risk pregnancy.

Follow Shannon on TikTok @tiktokbabydoc, Facebook @babiesafter35, and Instagram @babiesafter35.

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