Brachial palsy is a loss of movement or weakness of the arm that occurs when the collection of nerves around the shoulder are damaged during birth.

This bundle of nerves is called the brachial plexus.

The nerves of the brachial plexus can be injured during a difficult delivery from:

• The infant's head and neck pulling toward the side as the shoulders pass through the birth canal
• Pulling on the shoulders during a head-first delivery
• Pressure on the baby's raised arms during a breech (feet first) delivery

There are different forms of brachial palsy in an infant. The type depends on the degree of arm paralysis:

• Brachial plexus injuries typically affect only the upper arm.
• Erb's paralysis affects the upper arm and lower arm.
• Klumpke paralysis affects the hand. The infant may also have an eyelid droop on the opposite side.

The following increase the risk of brachial palsy:

• Breech delivery
• Larger-than-average newborn (such as an infant of a diabetic mother)
• Difficulty delivering the baby's shoulder after the head has already emerged (called shoulder dystocia)

Brachial palsy is less common now that delivery techniques have improved. Cesarean delivery is used more often when there are concerns about a difficult delivery.

Brachial palsy may be confused with a condition called pseudoparalysis. The infant has a fracture and is not moving the arm because of pain, but there has been no damage to the nerves.