VBAC refers to vaginal delivery of a baby after a previous pregnancy was delivered by cesarean delivery.

In the past, pregnant women who had one cesarean delivery would automatically have another. But research shows that, for many women who had prior cesarean deliveries, attempting to give birth vaginally—called a trial of labor after cesarean delivery (TOLAC)—and VBAC might be safe options in certain situations.

In fact, NICHD research shows that among appropriate candidates, about 75% of VBAC attempts are successful. A 2010 NIH Consensus Development Conference on VBAC evaluated available data and determined that VBAC was a reasonable option for many women.

NICHD-supported researchers also developed a way to calculate a woman's chances of a successful VBAC. Please note that this calculator only determines the likelihood of successful VBAC; it does not guarantee success.

Women should discuss VBAC and TOLAC with their health care providers early in pregnancy to learn whether these options are appropriate for them. Providers are encouraged to discuss plans for VBAC or refer women to a facility that can support VBAC when it is medically safe to consider.

Many women who have previously had a caesarean section can safely give birth vaginally. This is commonly referred to as 'vaginal birth after caesarean section' or VBAC.

The benefits of VBAC are:

• lower risk of developing complications than with repeat elective caesarean section
• avoiding other risks associated with surgical procedures (such as infections, deep vein thrombosis, increased blood loss)
• faster recovery
• generally less risk for the baby (for example, there is a decreased risk of your baby being admitted to a special care nursery for respiratory problems).

One of the risks associated with VBAC is rupture of the uterine scar. About one in every 200 VBACs attempted results in rupture of the uterine scar. For those women who do have a uterine rupture, there is an increased risk of hysterectomy and stillbirth.

If you have had a previous caesarean section, to make an informed decision, it is recommended that you discuss and clarify the information with your doctor or midwife, and ask what types of care and support your hospital offers for women choosing VBAC.

VBAC may be safe and appropriate for some women, including those:

• Whose prior cesarean incision was across the uterus toward its base (called a low-transverse incision)—the most common type of incision. Note that the incision on the uterus is different than the incision on the skin.
• With two previous low-transverse cesarean incisions
• Who are carrying twins
• With an unknown type of uterine incision

Benefits of VBAC include:

• No abdominal surgery
• A lower risk of hemorrhage and infection compared with a C-section
• Faster recovery
• Potential to avoid the risks of many cesarean deliveries, such as hysterectomy, bowel and bladder injury, blood transfusion, infection, and abnormal placenta conditions
• Greater likelihood of being able to have more children in the future

If labor fails to progress or if there is another problem, a woman may need a C-section after trying TOLAC. Most risks associated with C-section after TOLAC are similar to those associated with choosing a repeat cesarean. They include:

• Uterine rupture
• Maternal hemorrhage and infection
• Blood clots
• Need for a hysterectomy