Topic Overview

The most rare yet most serious risk of vaginal birth after cesarean (VBAC) is that the scar on the uterus may break open (rupture) during labor. Women who have a low transverse cesarean scar have a lower risk of rupturing than women who have a vertical incision scar. About 5 to 9 out of 1,000 women (0.5% to 0.9%) with a low transverse scar have a uterine rupture during a trial of labor.¹

A woman's risk of uterine rupture increases with:

• Each additional uterine surgical scar.
• Any uterine scar that reaches above the lower, thinner part of the uterus, such as a vertical (classical) scar.
• The use of medicine to start (induce) labor. Some doctors avoid the use of any medicine to start a VBAC trial of labor. Other doctors are comfortable with the careful use of certain medicines to start labor or strengthen labor, such as oxytocin.

It is likely that the women who have a rupture have other risk factors, which are things that make them more likely to have this complication.

Having had a vaginal delivery during another pregnancy lowers the risk of uterine rupture during VBAC. Women who have delivered vaginally and later had a cesarean delivery have about one-fourth the risk of women who have had a cesarean delivery but no vaginal delivery.¹

In the rare event that a uterine scar ruptures, it can be dangerous to both the mother and her infant.

Depending on severity, a rupture can:

• Be mild and harmless.
• Often be repaired. If it is not repairable, the uterus is removed (hysterectomy).
• Cause severe maternal bleeding and a decrease in oxygen to the baby.
• Cause fetal brain damage or death.