Induction of labour by pharmacological and physiological doses of intravenous oxytocin.

In addition to membrane rupture, pharmacological doses of oxytocin (2.6 mU/minute rusing stepwise to 422.4 mU/minute) were used in 134 patients and the results compared to those obtained in 144 patients given only physiological doses of oxytocin (2.6 to 13.2 mU/minute). Pharmacological doses of oxytocin gave better results in terms of induction-delivery intervals, incidence of failed inductions and puerperal morbidity. The incidence of hypertonus was similar in both groups and unrelated to oxytocin doses. A uterine activity of 276 Montevideo units, modified to 200 to 220 Montevideo units for grande multiparae, is defined as the goal of oxytocin treatment in induction of labour. A sign of imminent uterine tetany in the intrauterine pressure curve (the 'damping sign') is described.