3 Dec

Most mothers in the United States who want to labor for a VBAC still face resistance from their physician or hospital despite clear evidence that VBAC is a reasonable choice for women with a prior cesarean birth.

The American College of Obstetricians and Gynecologists (ACOG) has published and revised several VBAC clinical practice guidelines, the last time in 2010. Although the 2017 revisions seem to be the most supportive of VBAC to date, unfortunately the guidelines are not enforceable. Physicians and hospitals who support VBAC choose to do so voluntarily. It is important for mothers to become familiar with ACOG’s guidelines so that they can start a conversation with their provider during pregnancy and make an informed decision about how and where they want to give birth. Care providers are required to educate mothers about the benefits and risks of VBAC and elective repeat cesarean. Mothers have the right to accept or refuse the physician’s recommendations.

Many mothers today are still told they can’t labor for a VBAC if they are past-due, if their baby is “too big,” or if they have had two prior cesareans. However, ACOG’s guidelines support VBAC in those situations. The College recommends that “…individual circumstances must be considered in all cases.” Ultimately, it is the mother’s choice.

The following are highlights of ACOG’s Practice Bulletin, Number 184, Vaginal Birth After Cesarean Delivery.

“The decision to attempt TOLAC (trial of labor after a cesarean) is a preference-sensitive decision, and eliciting patient values and preferences is a key element of counseling.”

Benefits and Risks of Planning a VBAC Compared to Planning an Elective Repeat Cesarean

Women who choose a trial of labor and have a VBAC avoid major abdominal surgery. They have lower rates of hemorrhage, thromboembolism (blood clot), infection, and a shorter recovery period. Because the overwhelming majority of women with a prior cesarean go on to have a routine repeat operation in a subsequent pregnancy, VBAC may decrease the risk of maternal complications related to multiple cesareans. Mothers who have a VBAC will avoid the risk of hysterectomy, bowel or bladder injury, blood transfusion, infection and placental complications such as placenta previa and accreta.

Both elective repeat cesarean and laboring for a VBAC are associated with maternal and neonatal risk. VBAC is associated with fewer complications than elective repeat, but having a cesarean after laboring for a VBAC incurs higher complications. A mother’s risk of morbidity is related to her odds of having a VBAC.

The Odds of Having a VBAC

Mothers with one prior low-segment uterine scar who labor for a VBAC have a 60-80% of having a vaginal birth. The odds are the same for mothers with two prior cesareans. For mothers carrying twins, the odds of having a VBAC are also the same, with no increased risk of rupture or maternal and perinatal complications.

The probability of having a VBAC is somewhat lower for women who are older or heavier, whose pregnancy goes beyond 40 weeks, who are expected to have a “big baby”, whose labor is induced or augmented, and for women who labor less than 19 months after their prior cesarean. Although the odds are lower for VBAC, ACOG states that these are not reasons to prevent mothers from laboring for a VBAC. Care for women should be individualized. 


Women with a prior cesarean who are carrying a breech in the current pregnancy have similar rates of successful breech versions (ECV) as mothers without a uterine scar. A mother with a prior cesarean birth can elect to have a version for breech this time to avoid a cesarean.

Mothers who have had a prior vaginal birth, a prior cesarean for a breech or choose not to have an epidural for pain relief have a higher chance for a VBAC.

ACOG warns that trying to predict the odds of having a VBAC based on the use of current prediction models does not improve outcomes.

Although ACOG does not mention these factors in their guidelines, evidence shows that mothers who choose to have a midwife as a primary caregiver, a doula at their birth, or choose to give birth in a birth center have higher odds for a spontaneous vaginal birth.

When compared with expectant management (no interventions), labor induction is associated with lower odds of cesarean at 39, 40, and 41 weeks gestation.

The Risk of Uterine Rupture

The risk of uterine rupture with a low-transverse uterine incision is 05-0.9% with one prior cesarean. Less than 1%. The risk is similar for women with one low vertical uterine scar. ACOG states that the risk of rupture reported in the literature is between .09% to 3.7% with more than one prior cesarean. However, the medical community has not reached consistent conclusions in comparison to only 1 previous incision.

Women with one prior cesarean with an unknown scar may plan a VBAC unless her care provider suspects a previous classical scar for preterm gestational age. Rates of success and uterine rupture are similar to women with documented low-transverse uterine incision.

If a mother had a prior rupture of a low-segment uterine scar the chance of a repeat rupture while laboring for a VBAC is 6%.

The guidelines suggest that mothers with a previous classical or T incision, or placenta previa should not labor for a VBAC. With an upper segment uterine scar the risk of rupture is reported to be 15% to 32%.

Induction or augmentation of labor remains an option for women who want to labor after a prior cesarean, but the risk of uterine rupture is higher.

Misoprostol (prostaglandin E1 ) should not be used for cervical ripening or labor induction for women who choose to labor for a VBAC since it increases the risk for uterine rupture.

Pain Relief

An epidural may be used for pain relief. It does not mask the signs or symptoms of pain associated with a uterine rupture, however mothers need to be given additional time to give birth.   

Place of Birth

ACOG states that “vbac should be attempted at facilities capable of performing emergency deliveries.” This statement is perhaps the most important one in the new guidelines. Unlike the 2010 guidelines, it leaves no doubt that in fact all hospitals, including Level I centers (community hospitals) without 24/7 anesthesia and a physician capable of performing a cesarean can care for women who plan a VBAC.

This recommendation reflects the guidelines in Levels of Maternal Care which state that women planning a VBAC should be cared for in a facility with the “ability to begin emergency cesarean delivery within a time interval that best considers maternal and fetal risks and benefits with the provision of emergency care.” All women who labor are at risk for complications (cord prolapse, non-reassuring fetal heart rate, premature separation of the placenta) that may require an emergency cesarean, as are women who labor for a VBAC.

As in prior VBAC guidelines, ACOG does not recommend laboring for a VBAC at home. Ironically, it has been restrictive guidelines and hospital bans on VBAC that have led many women to choose a home VBAC associated with increased risks rather than comply with a forced repeat cesarean.

New Time Frame for Labor

Before recommending a cesarean for failure to progress, care providers should know that women who have not had a prior vaginal birth have a similar labor pattern to nulliparous women. That is women are not considered in active labor until they have reached 6cm of dilation. Progress in labor should be evaluated with the same standards as for first labors. Mothers who choose an epidural for pain relief also need more time to give birth.

ACOG Respects Women’s Informed Choice

“After counseling, the ultimate decision to undergo TOLAC or a repeat cesarean delivery should be made by the patient in consultation with her obstetrician or other obstetric care provider.”

Although ACOG has released their most progressive VBAC guidelines to date, it is up to physicians and hospitals to provide safe care for mothers who want to labor for a VBAC. Providers who do not support VBAC are contributing to the risks of multiple repeat operations.


For additional resources about VBAC see online educational modules of the VBAC Education Project.







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