Vaginal birth after cesarean (VBAC) is a vaginal childbirth after a woman has previously delivered a baby by cesarean section. Although VBAC is a safe choice for most women, it can have some risks for both the mother and the baby.

In rare cases, a cesarean scar on the uterus tears open, or ruptures, during VBAC. This can be life-threatening, causing severe blood loss in the mother and lack of oxygen for the baby.

Women with any of the following major risk factors for a rupture of the cesarean scar are advised not to try VBAC:

• A uterine scar that is not low and horizontal
• Two cesarean scars and no past vaginal delivery
• Three or more cesarean scars
• Pregnant with triplets or more
• Pregnant with twins, in some cases
• A medical condition or problem with the placenta that could complicate a vaginal delivery, such as when the placenta has grown abnormally low in the uterus (placenta previa)

There are other factors that can make VBAC unsafe.

A woman who chooses VBAC is closely monitored. As with any labor, if the mother or baby shows signs of distress, an emergency cesarean section is performed.