The efficacy of short-term gonadotrophin-releasing hormone agonists versus human chorionic gonadotrophin to enable oocyte release in gonadotrophin stimulated cycles.

One of the reasons for failure to conceive following human menopausal gonadotrophin (HMG) therapy may be due to non-release of oocytes from the follicles. We hypothesized that by using a gonadotrophin-releasing hormone agonist (GnRHa) for a short duration, endogenous release of luteinizing hormone and follicle stimulating hormone may enable oocyte release to occur, similar or superior to the effect of human chorionic gonadotrophin (HCG). This study attempted to compare the efficacy of HCG versus the GnRHa leuprolide acetate to release oocytes and achieve pregnancies and to compare the effectiveness of leuprolide acetate versus a combination of HCG with HMG to release oocytes. Unfortunately due to lack of prior data, many patients preferred to reject leuprolide acetate in favour of HCG, resulting in three times as many patients being treated with HCG in cycle 1; 78.2% of oocytes were released following leuprolide acetate versus only 55.7% with HCG. Interestingly, 87.5% of those females in whom oocyte release failed in cycle 1 with HCG did indeed release with leuprolide acetate in cycle 2, but none of these previous failures released with HCG in cycle 2. Pregnancy rates were equal in those women releasing oocytes, whether treated with HCG or leuprolide acetate. These preliminary data justify a larger randomized study.