Comparison of 25 and 50 microg vaginally administered misoprostol for preinduction of cervical ripening and labor induction.

Our purpose was to compare the efficacy of 25 microg and 50 microg intravaginally administered misoprostol tablets for cervical ripening and labor induction. Either 25-microg (n: 58) or 50-microg (n: 56) misoprostol tablets were randomly administered intravaginally to 114 subjects with an unripe cervix for labor induction. The physician was blinded to the medication. Intravaginal misoprostol was given every 4 h until the onset of labor. The mean Bishop score before misoprostol administration was 2.1 +/- 1.6 in the 25-microg group and 2.0 +/- 1.4 in the 50-microg group (p > 0.05). With the 25-microg dose the time until delivery was significantly longer (991.2 +/- 514.4 min vs. 703.12 +/- 432.6 min in the 50-microg group). The use of oxytocin augmentation was significantly higher in the 25-microg group (63.8%) than the 50-microg group (32.1%; p < 0.05). The proportions of patients with tachysystoles and hypersystoles were not significantly different between the two groups (19 and 6.9%, respectively, in the 25-microg group and 25 and 17.8%, respectively, in 50-microg group; p > 0.05). Overall, in the 25-microg group more women achieved vaginal delivery (79.3 vs. 60.7%; p < 0.05). The rate of cesarean sections due to non-reassuring fetal status was higher in the 50-microg misoprostol group (28.6 vs. 10.3%; p < 0.05). The number of neonates with a low 1-min Apgar score (<7) was significantly higher in the 50-microg misoprostol group (26.8 vs. 8.6%; p < 0.05), but 5-min Apgar scores and umbilical artery blood gas values at the time of delivery were not significantly different between the groups (p > 0.05). One patient in the 25-microg group suffered a ruptured uterus. Intravaginal administration of 25 microg of misoprostol is a clinically effective labor induction regimen and has the least adverse effects and complications.