For how long should oxytocin be continued during induction of labour?

Objective: To answer the question of whether oxytocin induction of labour should be discontinued when active labour begins. Design: We enrolled patients admitted for induction of labour with oxytocin. Exclusion criteria for induction of labour included non-vertex presentation, past history of more than one caesarean delivery, multiple pregnancies, non-reassuring fetal heart rate before induction of labour and estimated fetal weight of more than 4250 g. Setting: Department of Obstetrics and Gynecology, Ha'Emek Medical Center, Afula, Israel. Population: Patients who were admitted for induction of labour in Ha'Emek Medical Center from 1st February 1998 to 29th February 2000. Methods: Patients were randomly divided into two groups. In group A, infusion of oxytocin was incremental until 5 cm dilation and maintained at the same level from that point throughout the labour. In group B, infusion of oxytocin was incremental but was discontinued when cervical dilatation reached 5 cm. Comparison between the two groups was made using Wilcoxon rank-sum test and Fisher's exact test. Main outcome measure: Primary outcome variable was duration from induction to delivery. The secondary outcome variables included: duration of labour stages, maximal dosage and total amount of oxytocin used, the use of analgesia, abnormalities in fetal heart rate and episodes of uterine hyperstimulation. We also recorded mode of delivery, together with maternal and neonatal outcome. Results: One hundred and four patients participated in this study. The active phase of labour was shorter in group B compared with group A, but this difference was not statistically significant (2.6 ± 2 vs 3.3 ± 2.9, p = 0.07). In group A there were six caesarean deliveries and in group B only three. No significant differences were found when the other outcome parameters were compared. Conclusions: There is no advantage in continuing oxytocin infusion after the onset of active labour.