NEW YORK (Reuters Health) – For women giving birth, a high-dose oxytocin regimen results in a shorter duration of labor without increasing the c-section rate or adversely affecting other outcomes, according to a report in the August issue of Obstetrics & Gynecology.

The authors explain that oxytocin is used in up to 50% of births in some hospitals, but there is wide variation in the initial dose and dosing schedule. To examine the effects of different oxytocin regimens, they analyzed data on 15,054 women from the Consortium on Safe Labor, a collaborative study by the National Institutes of Health with 12 institutions across the United States.

Dr. Jun Zhang, at Shanghai Jiaotong University School of Medicine in China, and colleagues in the US grouped the women by the starting and incremental dose of oxytocin: 2,691 were given 1 milliunit/min, 4,994 received 2 milliunits/min, and 7,369 were given 4 milliunits/min.

The team found that duration of the first stage of labor in nulliparous women in the three dosage groups was 10.2, 8.9 and 8.5 hours, respectively. The difference between the low dose and higher doses was significant (p<0.001). The corresponding figures for multiparous women were 7.2, 6.6 and 6.1 hours (p<0.001).

There was no significant difference in the duration of the second stage of labor, according to the report.

The rate of cesarean delivery among nulliparous women was lower in the 4-millliunits/min group (14%) compared with the other two regimens (17%), but the difference disappeared after adjustment for potential confounders. For multiparous women, rates were also not significantly different, ranging from 2.2% with the high dose to 3.7% with the low dose.

Among nulliparous women, no other maternal and neonatal outcomes differed significantly in the three dosing groups, except for a trend toward an improved Apgar score with higher oxytocin doses. In multiparous women, high-dose oxytocin was associated with a reduced risk of meconium staining, chorioamnionitis, and newborn fever, Dr. Zhang and colleagues report.

Summing up, they conclude, “Our study found that high-dose oxytocin regimen (starting dose at 4 milliunits/min and increments of 4 milliunits/min) is associated with a shorter duration of the first stage of labor in both nulliparous and multiparous women without increasing the cesarean delivery rate or adversely affecting perinatal outcomes.”

Reference:
Oxytocin Regimen for Labor Augmentation, Labor Progression, and Perinatal Outcomes
Obstet Gynecol 2011;118:249–256.