Randomized, double-masked comparison of oxytocin dosage in induction and augmentation of labor.
OBJECTIVE
To test the hypothesis that high-dose oxytocin, when used in a masked fashion, would result in shorter labors and less need for cesarean delivery.


METHODS
We conducted randomized, double-masked trials of high-dose compared with low-dose oxytocin for augmentation and induction of labor. Patients were randomly assigned to receive oxytocin by either a low-dose protocol (1.5 mU/minute initially, increased by 1.5 mU/minute every 30 minutes) or a high-dose protocol (4.5 mU/minute initially, increased by 4.5 mU/minute every 30 minutes). Oxytocin solutions were prepared by a central pharmacy and infusion volumes (mL/hour) were identical, thus ensuring double masking.


RESULTS
A total of 1307 patients were randomized (induction, 816; augmentation, 491). In the group receiving oxytocin for induction, high-dose oxytocin was associated with a significant shortening of labor (oxytocin to complete dilatation: 9.7+/-0.3 compared with 7.8+/-0.2 hours, P<.001; oxytocin to delivery: 10.5+/-0.3 compared with 8.5+/-0.3 hours, P<.001). The cesarean delivery rate with low-dose oxytocin was 15.0%, compared with 11.3% with high-dose oxytocin (P = .17). For nulliparous women undergoing induction, cesarean delivery rates were as follows: Total 17.3% (low dose) compared with 11.7% (high dose), P = .15; cephalopelvic disproportion 11.9% (low dose) compared with 5.9% (high dose), P = .06. When used for augmentation, high-dose oxytocin again was associated with a significant shortening of labor without a significant difference in cesarean birth rates. No differences in neonatal outcomes were noted between the groups for either augmentation or induction.


CONCLUSIONS
When used in a double-masked fashion, high-dose oxytocin is associated with significantly shorter labors without any demonstrable adverse fetal or neonatal effects.
Merrill
D C
DC
Department of Obstetrics and Gynecology, University of Iowa College of Medicine, Iowa City, USA. dmerrill@wfubmc.edu
Zlatnik
F J
FJ
D000328:Adult; D003365:Costs and Cost Analysis; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007751:Labor, Induced; D010121:Oxytocin / Q000008:administration & dosage* / Q000191:economics; D011247:Pregnancy; D011256:Pregnancy Outcome; D013997:Time Factors
D010121:Oxytocin