Brachial plexus injuries have a wide spectrum of nerve impairment. Fortunately most begin anti-gravity recovery of shoulder, elbow, wrist and hand function in the first few months of life. If that is the case with your child (he or she can lift their hand towards their mouth in a sitting position; open his or her fingers wide, lift their arm to the shoulder level), then recovery will probably be full. However, if your child has no or minimal signs of recovery in the first three months of life, you should work with your primary care physician to (1) participate in a therapy program to maintain full range of motion of all joints (2) seek consultation regarding indications for nerve surgery.

(UBPN thanks Dr. Peter Waters for contributing this answer)