Efficacy of different starting doses of oxytocin for induction of labor.

One thousand twenty inductions of labor by amniotomy and continuous infusion of oxytocin at the Royal Women's Hospital were reviewed. Three different starting rates of infusion of oxytocin were used by altering the concentration to 2, 5, or 10 U/L. There was no difference in success of induction as measured by induction-to-delivery interval or by rate of vaginal delivery using higher initial concentrations of oxytocin. Higher pre-induction Bishop scores were associated with shorter labors and more vaginal deliveries. This study was retrospective and nonrandomized, but within these limits it suggests that "low-dose" oxytocin infusion is effective for induction of labor and may be associated with fewer hazards than are higher doses.