Infants born by ERCS are at increased risk for birth trauma
such as fetal lacerations caused by the surgical knife used to make the C/S incision.
However, brachial plexus injuries are more common with VBAC as compared to ERCS. The brachial plexus is a network of nerves originating in the spinal cord, and innervating to the shoulder, arm and hand. Brachial plexus injuries are caused by damage to those nerves.
Injury to this area it most commonly associated with shoulder dystocia, an impaction of the infant's shoulder behind the maternal symphysis pubis (pubic bone). The lateral traction on the head, as part of the corrective maneuvers to deliver the infant during a shoulder dystocia, stretches the brachial plexus, leading to injury 4%-40% of the time.
Studies of brachial plexus injury show an overall risk of between 1:2500 to 1:250 live births. An incidence of brachial plexus injury in infants born by VBAC is 1.8:1,000 compared to 3:10,000 among infants born by ERCS.
Therefore, the risk of brachial plexus injuries during VBAC is no greater than that of normal vaginal deliveries, but greater than in ERCS.