The author reviews the obstetric literature with regard to factors predisposing to or predicting the occurrence of brachial plexus injury in the newborn. Based on the evaluated data, it is concluded that, whereas there are identifiable predisposing factors for shoulder dystocia, to which the occurrence of brachial plexus injury is widely attributed, the predictive power of the various identifiable factors is generally low. The writer also quotes literary data which suggest that injury to the brachial plexus may occur in utero before labor and, thus, unrelated to arrest of the shoulders during the process of delivery. The contemporary literature contains diverse and often contradictory opinions which do not provide clear-cut guidelines for the practicing obstetrician for the prevention of brachial plexus injury. In some parts of the world a disproportionately large number of malpractice claims against obstetricians derive from such injuries. Therefore, the formulation of a consensus concerning the definition of shoulder dystocia, the identification of preventive measures to be utilized to avoid its occurrence and the required clinical management in case of arrest of the shoulders are unresolved problems that the medical profession needs to address.