Vaginal birth after caesarean (VBAC)

What it is

VBAC is offered where there has been one previous Cesarean section and the pelvis is adequate. The success rate is 60% to 80%, with 70% the number given; if the woman has had a previous vaginal delivery it is 90%.

Causes and risk

Success is more likely with age under 40yrs, a prior vaginal delivery, a favorable cervix, and a cause of the previous CS that is not recurrent. Failure is more likely with age over 40 yrs, 2 or more CS, an EFW over 4kg in DM or over 4.5 in normal women, and augmentation or IOL.

VBAC is contraindicated by what comes from the previous Cesarean, which is a classical or T shape incision, a previous uterine rupture, or a previous myomectomy; and by obstetric factors, which are malpresentation, placenta previa and accreta, pre-eclampsia, IUGR, and the medical ones: seizure, heart, asthma, renal.