A comparison of two methods of labor induction with vaginal misoprostol

To evaluate if labor induction with 50 microg of vaginal misoprostol twice per day is as effective as and safer than 100 microg used once per day.

Misoprostol was used to induce labor in 204 consecutive pregnant women assessed as needing labor induction, 104 at the University Hospital of the West Indies in Kingston, Jamaica, and 100 at the Victoria Jubilee Hospital, also in Kingston. At the former institution the women were administered 100 microg of misoprostol once per 24 h and at the latter 50 microg every 12 h. The doses were repeated if there was no cervical change or if the woman was not in labor. Bishop scores were determined before initiation of induction and again 12 h later. Women's records were reviewed after 24 h to determine delivery outcome.

The indications for labor induction were similar in each group. There was no significant difference in the group demographics. In the group given 50 microg of misoprostol twice per day the mean time+/-S.D. from insertion of misoprostol to delivery was significantly shorter than in the other group (560.14+/-269.20 min vs. 729.90+/-471.65 min; P<0.01), and the percentage of women who were delivered within 12 h was higher (75% vs. 56.8%; P<0.002). There was no significant difference between the two groups in the rate of cesarean births, the need for oxytocin, or blood loss. Only two patients experienced uterine hyperstimulation, both in the group that had received 100 microg of misoprostol per day. There was no significant difference between the two groups in the birthweight of the neonates and in the number of neonates with Apgar scores less than 7 at 1 min and 5 min. There were, however, significantly fewer neonates who needed resuscitation (6% vs. 14.7%; P=0.04) and admission to the special care nursery (7% vs. 17%; P=0.03) in the group that had received 50 microg of misoprostol twice per day.

A dose of 50 microg of misoprostol twice per day appears to be more efficient and safer than a dose of 100 microg once per day, but this may partially be due to weaknesses in the study design.