A comparison of two dosage regimens of oral misoprostol for labor induction at term

251 women with indications for labor induction at term were randomised to receive either 50 or 100 microgs of oral misoprostol, repeated every 4 h to a maximum of 5 doses. Parous women in the higher dose group received 50 microgs as their first dose, subsequent doses being 100 microgs. Women who failed to respond to the 5 doses of misoprostol had the option of having vaginal PGE2 gel. The primary outcome measure was the induction to delivery interval in those who delivered vaginally. Patient satisfaction was assessed by postnatal questionnaire.

The induction to vaginal delivery interval, although shorter in the 100 microgs group was not statistically significant (26.8 versus 33.7 h, mean difference 6.9 h, 95% CI 0.4-13). There were, however, more failed inductions with misoprostol in the 50 microgs group (12.7% Vs 4.8%, RR 2.6, 95% CI 1.07-6.5). There were no differences in the modes of delivery, number of caesarean sections for fetal distress or in the neonatal outcomes in the two groups. Most patients, 83% and 92% in the 50 and 100 microgs, respectively, were satisfied with their inductions, and 64% of patients would prefer to have the inducing agent given orally if they were to have another induction.

Oral misoprostol is effective in inducing labor and seems acceptable to patients. Both the 50 and 100 microgs dose regimens have a reasonable safety profile, but in view of the higher incidence of failed inductions with the 50 microgs dosage, the 100 microgs dose regimen may be the preferred dose regimen.