A randomized comparison of oral and intravaginal misoprostol for labor induction.

OBJECTIVE: To compare oral misoprostol (100 microgram) to vaginal misoprostol (25 microgram) for cervical ripening and labor induction.

METHODS: Two hundred thirty-six women with medical or obstetric indications for labor induction and undilated, uneffaced cervices were assigned randomly to receive 100 microgram of oral or 25 microgram of vaginal misoprostol every 4 hours for 24 hours. Intravenous oxytocin was then given using a standardized protocol. We anticipated that 31% of women treated orally and 50% of women treated vaginally would deliver vaginally within 24 hours of starting labor induction.

RESULTS: Among 234 subjects, 121 received oral and 113 received vaginal misoprostol. The mean (+/- standard deviation [SD]) interval from start of induction to delivery was 1240 +/- 845 minutes for orally treated women and 1381 +/- 802 minutes for vaginally treated women (P =.06, log-transformed data). More orally treated women delivered vaginally in 24 hours than vaginally treated women (74 versus 54, P =.14, relative risk [RR] 1.14, 95% confidence interval [CI] 0.92, 1.40). One hundred six women (87.6%) who received oral misoprostol delivered vaginally, compared with 88 women (77.9%) who received vaginal misoprostol (P =.07). Oxytocin was given to 60 (49. 6%) orally treated and 59 (52.2%) vaginally treated subjects (P =. 69). More women in the oral group had tachysystole, nine compared with two (P =.06), hypertonus, and hyperstimulation. Frequencies of intrapartum complications and birth outcomes were similar between groups.

CONCLUSION: Oral misoprostol 100 microgram and vaginal misoprostol 25 microgram were similarly effective for cervical ripening and labor induction. Oral administration was associated with trends toward higher likelihood of vaginal delivery and more uterine tachysystole.