The "PRIM" study

Inass Osman, Fiona MacKenzie, John Norrie, Heather M. Murray, Ian A. Greer, Jane E. Norman

Research output: Contribution to journalArticle (Academic Journal)peer-review

49 Citations (Scopus)


OBJECTIVE: The purpose of this study was to compare the efficacy and safety profile of prostaglandin E2 with isosorbide mononitrate for cervical ripening before the induction of labor at term.STUDY DESIGN: Primigravid women were assigned randomly to receive either 40 mg of isosorbide mononitrate or 2 mg of prostaglandin E2. Efficacy outcomes were the cervical ripening effect of each agent and the time from treatment initiation to delivery. Safety outcomes were the incidence and frequency of maternal side effects and events that would be potentially hazardous for mother and baby during outpatient cervical ripening.RESULTS: Prostaglandin E2 was more effective than isosorbide mononitrate in inducing a change in modified Bishop score. Mean duration from treatment initiation to delivery was greater for isosorbide mononitrate than prostaglandin E2. There were no adverse events in the isosorbide mononitrate group that would contraindicate outpatient treatment. However, in the prostaglandin E2 group, 7% of the pregnancies had abnormal fetal heart rate patterns (P = .0002). Maternal satisfaction was significantly higher in the isosorbide mononitrate group.CONCLUSION: Although isosorbide mononitrate was less effective, maternal satisfaction was significantly greater. The safety profile of each agent was such that it would be reasonable to give isosorbide mononitrate, but not prostaglandin E2, on an outpatient basis.
Original languageEnglish
Pages (from-to)1012-1021
Number of pages10
JournalAmerican Journal of Obstetrics and Gynecology
Issue number4
Publication statusPublished - 2006

Bibliographical note

RIS file


  • Adult Cervical Ripening Dinoprostone Double-Blind Method Female Gels Humans Isosorbide Dinitrate Labor, Induced Nitric Oxide Donors Oxytocics Pregnancy


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