Randomized controlled trial of 50 and 100 mcg of misoprostol for induction of labor at term

A. Ghidini, C. Y. Spong, V. Korker, E. Mariani

Research output: Contribution to journalArticle

5 Scopus citations


To compare the safety and efficacy of two different regimens of misoprostol for labor induction at term, we conducted a randomized controlled trial on women presenting for induction of labor at ≥37 weeks' gestation. Eligible women were randomized to receive intravaginal misoprostol 50 μg every 4 h or 100 μg every 6 h until any of the following: 1) adequate contraction pattern (3 contractions/10 min); 2) dilatation >3 cm; 3) artificial rupture of membranes; or 4) signs of uterine hyperstimulation. Use of oxytocin during labor was at the discretion of the managing clinician. The main outcome variable considered for analysis was cesarean section rate. Secondary outcome measures were induction to delivery interval and neonatal outcome (Apgar scores, meconium staining, and umbilical artery pH). A total of 58 women were randomized to receive either misoprostol 100 μg (n=26) or 50 μg (n=32). The 100 and 50 μg groups had similar mean Bishop's scores at induction (4.0±2.3 vs 4.1±2.2, p=0.87), rates of nulliparity, use of epidural anesthesia, and oxytocin augmentation. The number of doses of misoprostol used was similar in the two groups (1.4±+0.6 vs 1.8±1.2). The mean±standard deviation time to delivery (hours) (11.9±7.3 vs 14.3±9.6 h, p=0.30) and cesarean section rate (35% vs 19%, p=0.30, relative risk: 1.8, 95% confidence interval 0.7-5.4) were not different in the 100 vs 50 μg group. Power analysis demonstrated that 132 women would be required in each group to achieve statistical significance in the primary outcome measure (α=0.05, β=0.80). Similarly, rates of 5-minute Apgar scores <7 (4% vs 3%, p=1.0), and of meconium passage (17% vs 25%, p=0.73) were not significantly different between the two groups.

Original languageEnglish (US)
Pages (from-to)128-130
Number of pages3
JournalArchives of Gynecology and Obstetrics
Issue number3
StatePublished - Aug 31 2001
Externally publishedYes


  • Labor induction
  • Misoprostol
  • Prostaglandins

ASJC Scopus subject areas

  • Obstetrics and Gynecology

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