Discontinuation of oxytocin in the active phase of labor

To show that early discontinuation of oxytocin will not increase the mean duration of the active labor phase in a clinically significant way.

Controlled non-inferiority study.

Department of Obstetrics and Gynecology, University of Caen, Clemenceau Hospital, France.

A total of 138 women with singleton pregnancy and a vertex presentation of over 34 gestational weeks, presenting a medical indication of induction of labor or a dystocia at onset of labor, from May 2005 to June 2006.

Two parallel groups were compared: continuation of oxytocin until delivery versus discontinuation of oxytocin at the onset of the active phase. The clinically acceptable increase in mean duration of the active phase of labor (non-inferiority margin) was set at 60 minutes.

Primary outcome measure was duration of the active labor phase. Secondary outcome measures included total duration of labor, parameters concerning oxytocin use, rates of uterine hyperstimulation and fetal heart rate (FHR) abnormalities, and mode of delivery. Some neonatal outcomes were also analyzed.

Equivalence of the two strategies (continuation vs. discontinuation of oxytocin) was not demonstrated (p=0.97 testing for non-inferiority), the active phase even being significantly longer by a mean of 113 minutes (p=0.0001 testing for superiority). The rates of cesarean sections, alterations of FHR and delivery hemorrhage were higher when oxytocin was continued, but not significantly. There were significantly more infants hospitalized in neonatology when oxytocin was continued (p=0.028).

Discontinuation of oxytocin at the onset of the active phase prolongs labor. We found no argument for discontinuing the infusion of oxytocin at the onset of the active phase.