Background: Labor induction for terminating pregnancy in term parturients with unripe cervix has been concerned for many years. Laminaria and misoprostol have routinely been used for labor induction. This study aimed to compare the efficacy of laminaria and misoprostol for a successful labor induction.

Materials and Methods: In this double-blind clinical trial, 100 singleton term parturients (age 18-45) with unripe cervix were randomly allocated into two equal groups: Laminaria and misoprostol. First group received misoprostol (25 µg/vaginal) and the second group a single dose of laminaria intracervically. Both groups were compared for induction time to the active phase of labor, induction time to the delivery, dilatation changes during the first 6 hours after drug administration, cesarean delivery rate, fetal distress, meconium staining and uterine hyperstimulation.

Results: During the first 6 hours after drug administration, the cervical dilatation changes in the laminaria group were 4.4 times more than the misoprostol group (P=0.001). There was no significant difference between the two groups in induction time to active phase of labor and induction time to delivery time. The cesarean frequency rate in the misoprostol group was higher than that in the laminaria group (P=0.017). Uterine hyperstimulation was more common in the misoprostol group than the laminaria one and the difference was statistically significant. During the labor process, rate of oxytocin administration in the misoprostol group was lower than the laminaria group (P<0.0001).

Conclusion: Laminaria seems to be more effective and safer than the misoprostol for cervical ripening however, for better results further studies with a larger sample size are recommended.