Induction of labor with pulsatile oxytocin.

In a prospective, randomized study, 106 patients underwent induction of labor with either pulsed (every 8 minutes) (n = 50) or continuous (n = 56) intravenous infusion of oxytocin. Maternal characteristics, gestational age at induction, induction-delivery interval, analgesia for labor, cesarean section rates, and newborn characteristics were similar in both groups. The mean +/- SEM total oxytocin administered was significantly less in the pulsed group (3564 +/- 487 mU) than in the continuous group (7684 +/- 844 mU; p less than 0.0001); the average dose of oxytocin administered per minute was significantly lower in the pulsed group (3.9 +/- 0.3 mU/min) than in the continuous group (7.8 +/- 0.4 mU/min; p less than 0.0001); the peak or highest administered dose of oxytocin expressed per minute was also signficantly lower in the pulsed group (9.6 +/- 0.8 mU/min) than in the continuous group (14.1 +/- 0.7 mU/min; p less than 0.0001). These significant differences persisted even when controlled for parity, Bishop's score of the cervix, and number of days induction of labor was carried out. Uterine hyperstimulation occurred infrequently in both groups (3.6% to 4.0%). The pulsed group required a significantly smaller infusion volume (25 +/- 14 ml) than the continuous group (780 +/- 84 ml; p less than 0.0001). Thus pulsatile administration uses significantly less oxytocin and infusion fluid but is as effective and safe as continuous infusion.