Dystocia in nulliparous women.

Dystocia is common in nulliparous women and is responsible for more than 50 percent of primary cesarean deliveries. Because cesarean delivery rates continue to rise, physicians providing maternity care should be skilled in the diagnosis, management, and prevention of dystocia. If labor is not progressing, inadequate uterine contractions, fetal malposition, or cephalopelvic disproportion may be the cause. Before resorting to operative delivery for arrested labor, physicians should ensure that the patient has had adequate uterine contractions for four hours, using oxytocin infusion for augmentation as needed. For nulliparous women, high-dose oxytocin-infusion protocols for labor augmentation decrease the time to delivery compared with low-dose protocols without causing adverse outcomes. The second stage of labor can be permitted to continue for longer than traditional time limits if fetal monitoring is reassuring and there is progress in descent. Prevention of dystocia includes encouraging the use of trained labor support companions, deferring hospital admission until the active phase of labor when possible, avoiding elective labor induction before 41 weeks' gestation, and using epidural analgesia judiciously.