Higher-dose oxytocin and hemorrhage after vaginal delivery: a randomized controlled trial.
OBJECTIVE
Higher-dose oxytocin is more effective than lower-dose regimens to prevent postpartum hemorrhage after cesarean delivery. We compared two higher-dose regimens (80 units and 40 units) to our routine regimen (10 units) among women who delivered vaginally.


METHODS
In a double-masked randomized trial, oxytocin (80 units, 40 units, or 10 units) was administered in 500 mL over 1 hour after placental delivery. The primary outcome was a composite of any treatment of uterine atony or hemorrhage. Prespecified secondary outcomes included outcomes in the primary composite and a decline of 6% or more in hematocrit. A sample size of 600 per group (N=1,800) was planned to compare each of the 80-unit and 40-unit groups to the 10-unit group. At planned interim review (n=1,201), enrollment in the 40-unit group was stopped for futility and enrollment continued in the other groups.


RESULTS
Of 2,869 women, 1,798 were randomized as follows: 658 to 80 units; 481 to 40 units; and 659 to 10 units. Most characteristics were similar across groups. The risk of the primary outcome in the 80-unit group (6%; relative risk [RR] 0.93, 95% confidence interval [CI] 0.62-1.40) or the 40-unit group (6%; RR 0.94, 95% CI 0.61-1.47) was not different compared with the 10-unit group (7%). Treatment with additional oxytocin after the first hour was less frequent with 80 units compared with 10 units (RR 0.41, 95% CI 0.19-0.88), as was a 6% or more decline in hematocrit (RR 0.83, 95% CI 0.69-0.99); both outcomes declined with increasing oxytocin dose. Outcomes were similar between the 40-unit and 10-unit groups.


CONCLUSIONS
Compared with 10 units, 80 units or 40 units of prophylactic oxytocin did not reduce overall postpartum hemorrhage treatment when administered in 500 mL over 1 hour for vaginal delivery. Eighty units decreased the need for additional oxytocin and the risk of a decline in hematocrit of 6% or more.


BACKGROUND
ClinicalTrials.gov, www.clinicaltrials.gov, NCT00790062.


METHODS
I.
Center for Women's Reproductive Health and Maternal-Fetal Medicine Division, Department of Obstetrics and Gynecology, University Hospital, University of Alabama at Birmingham, Birmingham, Alabama, USA. atita@uab.edu
Alan T N
AT
Tita
Jeff M
JM
Szychowski
Dwight J
DJ
Rouse
Cynthia M
CM
Bean
Victoria
V
Chapman
Allison
A
Nothern
Dana
D
Figueroa
Rebecca
R
Quinn
William W
WW
Andrews
John C
JC
Hauth
D000293:Adolescent; D000328:Adult; D016009:Chi-Square Distribution; D036861:Delivery, Obstetric; D004311:Double-Blind Method; D005260:Female; D006400:Hematocrit; D006801:Humans; D010120:Oxytocics / Q000008:administration & dosage* / Q000627:therapeutic use; D010121:Oxytocin / Q000008:administration & dosage* / Q000627:therapeutic use; D006473:Postpartum Hemorrhage / Q000517:prevention & control*; D011247:Pregnancy; D018709:Statistics, Nonparametric; D014593:Uterine Inertia / Q000517:prevention & control*; D055815:Young Adult
D010120:Oxytocics; D010121:Oxytocin