High-versus low-dose oxytocin for labor stimulation

The number of cesarean births for dystocia has increased dramatically in the United States. Central to the management of dystocia is correction of ineffective labor by oxytocin administration, and contemporary obstetric practice is to stimulate labor with a low-dose oxytocin regimen. We prospectively compared a low-dose oxytocin regimen (1-mU/ minute dosage increments) with a high-dose regimen (6-mU/minute dosage increments) in 2788 consecutive singleton cephalic pregnancies. The low-dose regimen was used first for 5 months in 1251 pregnancies, and the high-dose regimen in 1537 pregnancies during the subsequent 5 months. Indications for oxytocin stimulation were divided into augmentation (N = 1676) and induction (N = 1112). Labor stimulation was more than 3 hours shorter (P < .0001) with the high-dose oxytocin regimen and associated with a reduction in neonatal sepsis (0.2 versus 1.3%; P < .01). Uterine hyperstimulation was more common (55 versus 42%; P < .0001) with the high-dose regimen, but no adverse fetal effects were observed. High-dose augmentation resulted in significantly fewer forceps deliveries (12 versus 16%; P = .03) and fewer cesareans for dystocia (9 versus 12%; P = .04). Similarly, failed induction was less frequent with high-dose compared with low-dose oxytocin (14 versus 19%; P = .05). Although the high-dose induction regimen was associated with a significantly increased cesarean incidence for fetal distress (6 versus 3%; P = .05), the incidence of umbilical artery cord blood acidemia was not increased in this subset. Induction of labor with high-dose oxytocin is problematic because of risk-benefit considerations. Although induction failed less frequently with the high-dose regimen, cesarean for fetal distress was performed more frequently. In contrast, high-dose oxytocin to augment ineffective spontaneous labor minimized the number of cesareans done for dystocia.