Oxytocin augmentation or induction of labor in term pregnant women: a randomized controlled trial to evaluate a 15 - versus 40 - minute dose increment interval

Abstract

Objectives 1. To compare efficacy of a 15-vs. a 40-minute interval for increasing the dosage
oxytocin infusion in induction or augmentation of labor.
2. To determine whether an increase in the oxytocin dosage interval would decrease
the incidence of uterine hyperstimulation and other complications.
Design A randomized controlled trial study.
Setting Srinagarind Hospital, Faculty of Medicine, Khon Kaen University.
Subjects and Methods We included 210 full-term pregnant women requiring induction or
augmentation of labor by oxytocin infusion between September 1999 and June 2000. Patients
were randomly allocated by cealed envelope technic to incremental increases at 15-minute
intervals (105 patients) or 40-minute intervals (105 patients). The main outcomes assessed
were efficacy (duration and maximum dosage of oxytocin infusion, operatived delivery,
emergency cesarean section, neonatal outcomes), uterine hyperstimulation and other
complications (i.e. postpartum hemorrhage, precipitation of labor and suspected fetal
distress).
Results The 40-minute interval protocol resulted in significantly lower maximum dosage of
oxytocin infusion (p-value = 0.004) and less uterine hyperstimulation (RR 0.40,95% CI 0.21 -
0.75). There was a trend in reduction in the occurrence of suspected fetal distress (RR
0.61, 95% CI 0.36 -1.03), precipitation of labor (RR 0.66,95% CI 0.13 -3.31), postpartum
hemorrhage (RR 0.56, 95% CI 0.17-1.83), operative delivery (RR 0.8, 95% CI 0.61-1.22) and
emergency cesarean sections (RR 0.93,95% CI 0.57-1.53), but these differences did not
reach statistical significance. There were also no differences between groups in the duration
of oxytocin infusion or the number of days in hospital. Neonatal outcomes were unaffected by
the dosage interval.
Conclusions For the induction and augmentation of labor in full-term pregnancies an increased
oxytocin infusion rate at 40-minute intervals was superior to the 15-minute protocol in
reducing the maximum dosage of oxytocin infusion and reducing the incidence of uterine
hyperstimulation.