A RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED TRIAL OF THE SAFETY OFVAGINAL RECOMBINANT HUMAN RELAXIN FOR CERVICAL RIPENING

Objective: To assess the safety of vaginal recombinant human relaxin i n pregnant women treated before the induction of labor and to collect preliminary data on the efficacy of recombinant human relaxin in promo ting cervical ripening. Methods: In a multi-center, randomized, double -blind placebo-controlled trial, 40 women were studied before inductio n of labor because of post-dates. The women were randomized to receive either 1.5 mg recombinant human relaxin in 3% methylcellulose gel or gel only, placed into the posterior vaginal fornix after a cervical as sessment on the evening; before scheduled induction. If a subject did not go into spontaneous labor overnight, another cervical assessment w as performed 15 hours following treatment, immediately before the stan dard induction regimen of the hospital. Results: No important maternal or fetal-neonatal complications could be attributed to the drug. The differences between the recombinant human relaxin group and the placeb o group for all the outcome measures of efficacy did not achieve stati stical significance. Placebo patients were more likely to report moder ate or strong uterine contractions in the first 4 hours following trea tment than were the recombinant human relaxin-treated patients. Conclu sions: The use of recombinant human relaxin at a dose of 1.5 mg was no t associated with any significant maternal or fetal-neonatal complicat ions. The relatively small number of subjects in this study was chosen deliberately because this was the first use of the drug in pregnant s ubjects. Assessment of efficacy will require studies that include more patients and a range of relaxin doses.