For How Long Should Oxytocin Be Continued During Induction of Labor?

Abstract

There still is no agreement as to whether oxytocin, given to induce or augment labor, should be continued after active labor begins. The question is an important one because of the risk of uterine hyperstimulation, whichmay compromise the fetus or cause dysfunctional labor. Even uterine rupture is a possibility. This prospective, randomized study enrolled 104 women admitted for induction of labor with oxytocin. None had more than 1 previous cesarean delivery, and multiple pregnancies and a nonvertex presentation precluded participation. Also excluded were cases with a nonreassuring fetal heart rate before induction or an estimated fetal weight exceeding 4250 g. Group A patients received oxytocin incrementally until 5 cm of dilation was achieved and then at the same rate throughout labor. In group B patients, oxytocin was withdrawn at 5 cm of cervical dilatation. Induction began by infusing 1 mIU/min of oxytocin and increasing the dose by 1 mIU/min at 20-minute intervals until contractions occurred regularly at a rate of 3 to 5 every 10 minutes. The maximum dose rate allowed was 20 mIU/min. In both groups, the major indications for inducing labor were postdate pregnancy and rupture of membranes. Groups A and B did not differ significantly in the condition of the cervix before induction, the course of labor, or the analgesia used during labor. The active phase of labor was shorter in group B, but not to a significant degree. Oxytocin was stopped in 4 group A women because of a nonreassuring fetal heart rate pattern. It was restarted in 4 group B women when uterine activity was inadequate and labor arrested. There were 6 cesarean deliveries in group A and 3 in group B. All section deliveries were done because of nonprogressive labor or a nonreassuring fetal heart rate pattern. There were no maternal or neonatal complications. It seems possible to suspend oxytocin infusion at the start of the active phase of labor without prolonging labor, and there is no apparent reason not to do so.