Comparison of 25 and 50 μg Vaginally Administered Misoprostol for Preinduction of Cervical Ripening and Labor Induction

Abstract

Our purpose was to compare the efficacy of 25 µg and 50 µg intravaginally administered misoprostol tablets for cervical ripening and labor induction. Either 25-µg (n: 58) or 50-µg (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-µg group and 2.0 ± 1.4 in the 50-µg group (p > 0.05). With the 25-µg dose the time until delivery was significantly longer (991.2 ± 514.4 min vs. 703.12 ± 432.6 min in the 50-µg group). The use of oxytocin augmentation was significantly higher in the 25-µg group (63.8%) than the 50-µg 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-µg group and 25 and 17.8%, respectively, in 50-µg group; p > 0.05). Overall, in the 25-µg group more women achieved vaginal delivery (79.3 vs. 60.7%; p < 0.05). The rate of cesarean sections due to nonreassuring fetal status was higher in the 50-µg 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-µg 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-µg group suffered a ruptured uterus. Intravaginal administration of 25 µg of misoprostol is a clinically effective labor induction regimen and has the least adverse effects and complications.