Objectives: It is an almost assumption in obstetric literature that brachial palsy is due to extreme lateral traction on the fetal head during the last phase of delivery. In contrast, there have been reports in the neurologic literature of probable intrauterine origin of brachial plexus palsy. Data to dispute or support the latter view were sought.
Study design: With this overview in mind, our perinatal data base was searched for all instances of shoulder dystocia and independently for all diagnoses of brachial plexus impairment.
Results: Seventeen instances of brachial plexus impairment associated with shoulder dystocia were found. Twenty-two instances of brachial plexus impairment without mention of shoulder dystocia were ascertained. The characteristics of the two groups were remarkably different, especially in birth weight and in maternal age and parity.
Conclusions: The data are strongly suggestive that intrauterine maladaptation may play a role in brachial plexus impairment. Brachial plexus impairment should not be taken as prima facie evidence of birth process injury.