THE USE OF LONG-ACTING AND SHORT-ACTING FORMS OF GONADOTROPIN-RELEASING-HORMONE ANALOGS IN WOMEN UNDERGOING OOCYTE DONATION

Evidence accumulated in in-vitro fertilization (IVF) cycles suggests t hat the use of long-acting forms of gonadotrophin-releasing hormone an alogues (GnRHa) for pituitary desensitization may impair the outcome o f IVF as compared to classical short-acting formulations. Whether the negative effects are directed against the corpus luteum, the endometri um, or both is unknown. However, the presence of high affinity binding sites for gonadotrophin-releasing hormone (GnRH) in the human endomet rium suggests a possible role of these analogues on this target organ, affecting embryo implantation. In the present study, we tested direct effects of two different forms of GnRHa on implantation using the ovu m donation model. Patients were prospectively allocated to one of the three study groups: the short-acting form of the analogue leuprolide a cetate (group I; n = 64), the long-acting form of the same analogue (g roup II; n = 58), and the long-acting preparation of the analogue tryp torelin (group III; n = 61), A total of 68 cycles of embryo transfer w as carried out in group I, whereas 67 were performed in group II and 6 5 in group III. Cancellation rates were respectively 18.1, 17.3 and 18 .8% because of bleeding while being on the waiting list for anonymous oocyte donation. The number of oocytes donated, fertilization rates an d embryos replaced in each group were similar. As a result, pregnancy rate per transfer was 38.2, 49.3 and 44.6 % respectively. Implantation rates per embryo replaced were respectively 13.4, 19.1 and 17.0%, The se data suggest that the use of a long-acting form of GnRHa provides s uccess rates similar to the short-acting preparations, resulting in mo re convenient medication for patients with ovarian function included i n ovum donation programmes.