The reflex that the nurse would anticipate a problem with in this scenario is the Moro reflex. The Moro reflex is an involuntary startle reflex that is elicited by a sudden change in position or a loud noise. In newborns, the reflex is characterized by an extension and abduction of the arms followed by a return to a flexed position. This reflex is important for assessing the integrity of the nervous system in newborns. However, if the birth was prolonged due to fetal shoulder dystocia, the infant may have experienced trauma to the brachial plexus, which can result in weakness or paralysis of the affected arm. This can impact the normal development of the Moro reflex and other reflexes, and the nurse should monitor the newborn closely for any signs of brachial plexus injury.