Oral administration of misoprostol for labor induction: a randomized controlled trial

To evaluate the effectiveness, safety, and gastrointestinal tolerance of misoprostol taken orally for induction of labor, against our established protocol, with the interval from induction to vaginal birth as the primary outcome measure.

Two hundred seventy-five women who presented with indication for induction of labor were assigned randomly to receive either 50 micrograms of misoprostol orally every 4 hours as needed or treatment according to our established protocol (physician-chosen combinations of intracervical or vaginal prostaglandins every 4-6 hours, artificial rupture of membranes, and oxytocin infusion). Sample size was calculated with a two-tailed alpha = .05 and power of 95%.

The mean time (+/-standard deviation) to vaginal birth with oral misoprostol was 926 +/- 521 minutes versus 909 +/- 585 minutes with the established protocol, a nonsignificant difference. There were no clinically or statistically significant differences in maternal secondary outcome measures (cesarean rate, frequency of epidural use, perineal trauma, or manual removal of the placenta). There was no difference in frequency of maternal gastrointestinal side effects. Neonatal outcomes, including cord blood acid-base analysis, were not different.

Oral misoprostol may be a new option for labor induction. It appears to be no less effective or safe than our usual regimen for induction of labor at term and is well tolerated. Further studies are warranted to confirm the safety of this approach and to determine optimal dose and frequency of administration.