NEW YORK (Reuters Health) – For women in spontaneous labor but requiring labor augmentation, oral misoprostol is as effective as intravenous oxytocin, at team from the University of Texas Southwestern Medical Center, Dallas, reports in the December issue of Obstetrics & Gynecology.

“We are of the view that our study suggests that oral misoprostol is an effective agent for augmentation of labor, although this study has not established its safety when uncommon outcomes are considered,” conclude Dr. April T. Bleich and colleagues.

They note that oxytocin is usually used in the US for labor augmentation, but misoprostol could be a “logical” alternative. Before investigating misoprostol for labor augmentation, though, the team first undertook a dose-finding study which indicated that a 75-mg oral dose of misoprostol produced adequate uterine activity with the least risk of hyperstimulation.

For the current study, they randomized 350 women in spontaneous labor with cervical dilation of 4-8 cm and requiring labor augmentation to receive either IV oxytocin or 75-mg oral misoprostol.

Median time from admission to administration of the study drug was significantly shorter in the misoprostol group (330 minutes) than the oxytocin group (402 minutes), the authors report. “This difference is presumably due to the ease of administrating oral misoprostol compared with implementing an intravenous oxytocin infusion,” they suggest.

The interval from drug administration to delivery was not significantly different between the two groups, at 306 minutes with misoprostol and 276 minutes with oxytocin.

Rates of uterine hypertonus were significantly higher in the misoprostol arm than the oxytocin arm (24% vs 11%; p=0.002), the report indicates, but this was not associated with more c-sections (11% vs 10%) or any other adverse outcomes that the investigators measured.

However, Dr. Bleich and colleagues point out that while the study was large enough to assess the efficacy of labor augmentation with misoprostol, it was not powered to assess all aspects of neonatal and maternal safety. “That is, there is a real possibility that insufficient sample size may have hampered our ability to detect uncommon neonatal outcomes,” they caution.

That said, they conclude, “Oral misoprostol is an effective agent for augmentation of labor.”

Reference:

Oral Misoprostol for Labor Augmentation: A Randomized Controlled Trial

Obstet Gynecol 2011;118:1255–1260.