The American College of Obstetricians and Gynecologists convened the Task Force on Neonatal Brachial Plexus Palsy to develop a comprehensive report summarizing a scientific literature on this subject. Clinically, neonatal brachial plexus palsy (NBPP) presents in a newborn as a weak or paralyzed upper extremity, with the passive range of motion greater than the active. The overall incidence of NBPP, both transient and persistent impairment, is 1.5 per 1,000 total births. Multiple reports in the peer-reviewed literature describe the occurrence of NBPP without concomitant clinically recognizable shoulder dystocia at the time of both vaginal and cesarean delivery. Chapter 1 of the report details the incidence of NBPP.