Effects and clinical significance of GnRH antagonist administration for IUI timing in FSH superovulated cycles: a meta-analysis

OBJECTIVES: To compare the administration of GnRH antagonist in gonadotropin intrauterine insemination (IUI) cycles with cycles where no intervention took place.

DESIGN: Meta-analysis of published prospective randomized trials.

PATIENTS(S): Five hundred twenty-one patients who were administered a GnRH antagonist and 548 conservatively treated patients who served as control subjects were included in the meta-analysis.

STUDY SELECTION: Prospective trials were retrieved from Medline and Cochrane Library (last update October 2006). Random effect analysis was used in this meta-analysis. Two independent reviewers performed data extraction.

MAIN OUTCOME MEASURE(S): Clinical pregnancy rates.

RESULT(S): Six comparisons were retrieved including 1,069 patients. Higher pregnancy rates were found in the randomized controlled trials (odds ratio [OR] 1.56, 95% confidence interval [CI] 1.05-2.33) when a GnRH antagonist was added to a gonadotropin superovulated IUI protocol. Early published studies with smaller sample sizes showed stronger associations (OR 2.31, 95% CI 1.15-4.63) than later studies (OR 1.32, 95% CI 0.79-2.23).

CONCLUSION(S): From the randomized controlled trials of this meta-analysis, it is clear that allowing for follicle growth and avoiding premature LH rise, increased pregnancy rates are observed with GnRH antagonist administration. A parallel trend for multiple pregnancy rates in the GnRH antagonist group was observed, although this did not reach statistical significance. The flexible regimen was widely used. This meta-analysis of early data might enhance further research in this direction.