Induction of labor by oxytocin or prostaglandin E2.

Abstract

The efficacy and safety of oral PGE2 or intravenous infusion of oxytocin, in both cases combined with early amniotomy, for induction of labor on medical grounds, were compared in a randomized study of 200 women. After an initial dose of 0.5 mg, 1.0 mg of PGE2 was given at hourly intervals for up to 24 hours. Oxytocin was administered as an intravenous pump infusion, the dose being increased step wise up to 20 mIU/min. The two methods were equally effective. All patients went into labor and were delivered within approximately 24 hours. Of the total of 200 patients included in the study, 92 per cent were delivered vaginally and 8 per cent with Caesarean section. In 26 per cent the delivery was completed by vacuum extraction. The frequency of instrumental delivery was significantly lower in multiparous than in primiparous patients. If the patient was a multiparous woman and the modified Bishop score was 6 or more, the combined frequency of Caesarean section and instrumental delivery was for PGE2 2.5 per cent and for oxytocin 3.1 per cent.No difference was found in the health status of neonates following labor induction with PGE2 and oxytocin respectively.At the end of the 24‐hour observation period five patients were still in labor. These patients were delivered either by vacuum extraction (three patients) or by Caesarean section (two patients).The duration of labor was slightly longer (mean 1.1 hour) following oral PGE2 than following intravenous infusion of oxytocin, mainly due to a prolongation of stage I.The type of delivery following oral PGE2 or intravenous infusion of oxytocin in combination with early amniotomy was compared with that following spontaneous labor and following labor induction by oxytocin alone. The frequency of Caesarean section was the same but the frequency of instrumental delivery was lower in the former two groups of patients. The difference could at least partly be explained by a higher frequency of patients who obtained epidural analgesia in the randomized trial. Oral PGE2 or intravenous infusion of oxytocin combined with early amniotomy was obviously more effective than oxytocin alone for labor induction. With oxytocin alone, two days of infusion was required in 53.8 per cent and four or more days in 2.4 per cent of the patients.It may be concluded that oral PGE2 therapy combined with amniotomy is a valuable alternative to intravenous infusion of oxytocin for labor induction at or near term. The method is generally well accepted by the patient. The main advantage is the ease and simplicity of the treatment. Complications are rare, particularly in multiparous patients with good prospects of inducibility.