Brachial plexus is a collection of nerves that exit the spinal cord in the neck and supply nerve impulses to the arms. If a baby’s head is twisted or bent to an extreme degree during delivery, these nerves can be stretched or damaged to the extent that it results in partial or complete paralysis of the arm on one side, a condition known as Erb’s palsy.
Erb’s palsy often occurs when the baby is too large to fit through the birth canal after the delivery of the head. Since the head is normally the largest part of a baby, once the head is delivered, the rest of the body follows quickly and without difficulty. In cases where the baby is larger than eight pounds, the body is somewhat larger, making it difficult to pass through the birth canal.
Erb’s palsy often occurs when the baby is too large to fit through the birth canal after the delivery of the head. Since the head is normally the largest part of a baby, once the head is delivered, the rest of the body follows quickly and without difficulty. In cases where the baby is larger than eight pounds, the body is somewhat larger, making it difficult to pass through the birth canal.
Cephalopelvic disproportion (CPD), a condition in which the baby’s head or body is too large to pass through the mother’s pelvis, must be identified by the obstetrician before labor begins or in its early stages. Once diagnosed, the baby should be delivered by c-section to avoid birth injuries. Failure to diagnose this condition can result in a prolonged, difficult labor (dystocia).
With a larger baby, the shoulder can become trapped behind the pelvic bone after the head is delivered, a condition known as shoulder dystocia. When the obstetrician attempts to deliver the impacted shoulder, the nerves of the brachial plexus can be stretched. If the obstetrician uses excessive force, the nerves can be pulled from their attachment to the spinal cord, which is known as an avulsion. Avulsion usually results in complete paralysis of the arm and hand. At birth, the baby’s arm will appear limp.