COMPARISON OF BUSERELIN AND NAFARELIN IN IVF CYCLES AND IN SUBSEQUENTFROZEN-THAWED EMBRYO-TRANSFER CYCLES

Objective. To compare two gonadotropin-releasing hormone agonists for down-regulation prior to superovulation in in vitro fertilization/embr yo transfer treatment. Methods. Infertility patients (n=181) were rand omized to receive buserelin (1200 mu g/day, n=90) or nafarelin (800 mu g/day, n=91) intranasally starting in the luteal phase. Serum levels of LH, estradiol and progesterone were measured during the treatment. The cycles were compared with regard to number of oocytes, fertilizati on and implantation rates and achieved pregnancies. Results. Serum LH was lower after two weeks on buserelin: 1.8 (1.3-2.4) IU/L (median, wi th lower and upper quartile in parenthesis): than after nafarelin: 2.6 (1.8-4.0) IU/L, (p=0.0001). No other differences in serum hormone lev els could be detected. More oocytes were recovered in the buserelin gr oup: 13.0 (8.0-19.0) vs 11.0 (6.8-15.0), (p=0.046), but the fertilizat ion rate was higher in the nafarelin group (49.9% vs 45.1%, p=0.023). Implantation rate was higher in the nafarelin group (26.2% vs 15.5%, p =0.030), but there were an equal number of deliveries in both groups ( 20.9% vs 15.6% per started stimulation, p=0.420). In the subsequent fr ozen-thawed embryo transfer cycles the implantation rate was 21.1% (na farelin group) and 10.6% (buserelin group, p=0.067), the pregnancy rat e/ET was 31.7% and 17.0% (p=0.107) and the delivery rate was 22.0% and 10.6% (p=0.148), respectively. Conclusions. Differences exist in IVF- cycles down-regulated with buserelin or nafarelin which might affect e mbryo quality and treatment outcome.