Fortunately, injury to the major nerves to the upper extremity rare relatively rare in the United States, particularly in child delivery.  When they occur, however, there has been controversy as to when the best time is to intervene for those lesions which are expected to require end-to-end reconnecting and possibly even nerve grafting to restore function to the muscles that would normally be innervated.  A very nice prospective, multi-center study was just published in the Journal of Bone & Joint Surgery, 2020, Vol. 102, confirming that there was no advantage in doing this very difficult and aggressive surgery for a mean age of 10.7 months.  In other words, earlier surgery, i.e., an average of 4 months, does not lead to a better postoperative outcome.  It potentially makes the surgery safer for the infant and takes some of the burden off of the physician as to how fast the infant needs to be taken to surgery.