[Obstetrical brachial plexus palsy--etiopathogenesis, risk factors, prevention, prognosis].

Obstetrical brachial plexus palsy (OBP) complicates a small proportion of births. The incidence is believed to be 0.35 to 5 cases per 1000 live births. Risk factors of OBP included: 1/ large birth weight, 2/ shoulder dystocia and prolonged second stage of labour , 3/ instrumental vaginal delivery (forceps delivery, vacuum extraction), 4/ diabetes mellitus and mother's obesity, 5/ breech presentation, 6/ delivery an infant with OBP in an antecedent delivery. Historically, the cause of OBP was excessive lateral traction applied to the fetal head at delivery, in association with anterior shoulder dystocia. Not all cases of brachial plexus palsy are attributable to traction. Brachial plexus injury may be occurring in the absence of shoulder dystocia, in the posterior arm of infants with anterior shoulder dystocia and can be associated with cesarean delivery. Intrauterine factors may play some role in the etiology of the OBP. Many strategies have been proposed to prevent the occurrence of OBP--control of the birth weight, induction of labour, cesarean delivery, intensified management of gestational diabetes. About 10-20% of patients with injuries of the brachial plexus require surgical intervention for optimal results.