Induction of labor with oxytocin increases cesarean section rate as compared with oxytocin for augmentation of spontaneous labor in nulliparous parturients controlled for lumbar epidural analgesia.

STUDY OBJECTIVES: To study labor outcomes in parturients receiving oxytocin for augmentation or induction of labor, in the presence of labor epidural analgesia.

DESIGN: Retrospective study of data from a continuous quality improvement database.

SETTING: Tertiary-care hospital with more than 8000 deliveries per annum.

MEASUREMENTS AND MAIN RESULTS: Of the 1671 healthy nulliparous women with singleton pregnancies and who requested labor epidural analgesia at our institution, 675 patients received oxytocin during elective induction of labor, whereas 996 patients received oxytocin for augmentation of spontaneous labor. Measured variables were cervical dilatation at time of epidural analgesia request, epidural insertion to 10-cm time, duration of stage 2 of labor, normal spontaneous vaginal delivery rate, cesarean section rate, operative vaginal delivery rate, and baby weight. Women admitted for induction of labor requested epidural analgesia sooner than those who had their labor augmented (p < 0.001). The incidence of cesarean section was higher in the induced group (p = 0.008).

CONCLUSION: Patients who have their labor induced request analgesia sooner and are at a higher risk of cesarean section than are patients who go into labor spontaneously. Any study that purports to assess the effects of epidural analgesia in labor should distinguish between induced and augmented/spontaneous labor.