Brachial palsy is a condition where an infant's arm is partly or completely paralyzed at birth.

What is going on in the body?

Brachial palsy is a birth injury that can happen to newborns during delivery of the head and shoulders. The brachial plexus is a network of nerves that join together to form the nerves of the arm, hand, and fingers. If the brachial plexus is stretched during delivery, the newborn may have weakness or paralysis involving all or part of an arm.

What are the causes and risks of the condition?

The injury is more likely to happen if the baby is large and the bony outlet of the mother's pelvis is small, relative to the baby. The brachial plexus can be stretched if the person assisting in the delivery has to pull on the baby's head and neck in order to deliver the shoulders. It can also happen with breech delivery, if the baby's arms are extended above his or her head during the delivery.