The routine use of gonadotropin-releasing hormone agonists prior to in vitro fertilization and gamete intrafallopian transfer: a meta-analysis of randomized controlled trials**Supported by contract no. 91-R-559 from the Royal Commission on New Reproductive Technologies, Ottawa, Ontario, Canada.

OBJECTIVE: To assess the efficacy of gonadotropin-releasing hormone agonists (GnRH-a) used in ovulation induction for in vitro fertilization and embryo transfer (IVF-ET) and gamete intrafallopian transfer (GIFT). DESIGN: Meta-analysis of 10 trials comparing treatment cycle outcomes after GnRH-a (n = 914) with other ovulation induction protocols (n = 722) and 7 trials comparing outcomes after short flare-up (n = 368) with longer suppression (n = 476) GnRH-a protocols. MAIN OUTCOME MEASURES: The outcome of primary interest was clinical pregnancy rate (PR) per treatment cycle commenced. Data describing the amount of gonadotropin used, cycle cancellation rate, clinical pregnancy per ET, and multiple pregnancy and abortion rates were also analyzed. RESULTS: Clinical PR per cycle commenced was significantly improved after GnRH-a use for IVF (common odds ratio [OR] 1.80, 95% confidence interval [CI] 1.33 to 2.44) and GIFT (common OR 2.37, 95% CI 1.24 to 4.51). Clinical PR per embryo transfer was also significantly improved with GnRH-a use (common OR 1.40, 95% CI 1.01 to 1.95). Cycle cancellation was decreased (common OR 0.33, 95% CI 0.25 to 0.44), whereas spontaneous abortion rate was similar with and without GnRH-a use. Cycle cancellation and PRs after short flare-up and longer suppression protocols were similar between groups. CONCLUSIONS: This meta-analysis supports the routine use of GnRH-a for IVF and GIFT. Further research is needed, however, to assess the potential for increased rates of multiple pregnancy and ovarian hyperstimulation syndrome, which may be associated with this treatment.