High doses of gonadotrophin-releasing hormone antagonist in in-vitro fertilization cycles do not adversely affect the outcome of subsequent freeze-thaw cycles.

The clinical application of gonadotrophin-releasing hormone (GnRH) antagonists instead of GnRH agonists, to prevent spontaneous premature luteinizing hormone surge during ovarian stimulation for assisted reproduction treatment has been advocated. A recent, double-blind, dose-finding study, including six dosages of the GnRH antagonist ganirelix, in women undergoing ovarian stimulation with recombinant follicle stimulating hormone (FSH), has indicated that high doses of GnRH antagonist (1 or 2 mg once daily) are associated with a low implantation rate. This follow-up study reports on the pregnancy rate after replacement of cryopreserved embryos obtained in stimulation cycles of the above-mentioned trial. Ovarian stimulation was initiated on day 2 of the cycle, with daily injections of 150 IU recombinant FSH. Ganirelix (0.0625, 0.125, 0.25, 0.5, 1.0 or 2.0 mg) was administered once daily from stimulation day 6 onwards, up to and including the day of human chorionic gonadotrophin. Retrieved oocytes were fertilized by in-vitro fertilization (IVF) or intracytoplasmic sperm injection and a maximum of three fresh embryos was transferred. Excess embryos were frozen, and subsequently used in either natural or programmed cycles. Until June 1998, 11 ongoing pregnancies (12-16 weeks after embryo transfer) were achieved from 46 cycles in which embryos had been first frozen (23.9% per transfer). Six of these 11 patients had been treated with a high dose of ganirelix (1.0 or 2.0 mg) during the IVF cycles in which the embryos were obtained. In conclusion, our data suggest that high dosages of ganirelix do not adversely affect the potential of embryos to establish clinical pregnancy in freeze-thaw cycles.