Purpose: The administration of two GnRH analogues (buserelin and leuprolide acetate) in long and short protocols was evaluated prospectively. In the long protocol, the analogues were given from day 1 of the cycle for at least 14 days and then hMG administration was started, while in the short protocol the analogues were initiated from cycle day 1, adding hMG from day 3. The patients were divided into four groups according to the protocol used: Group I, buserelin-long; Group II, buserelin-short; Group III, leuprolide-long; and Group IV, leuprolide-short. Serum E2 levels on the day of hCG injection and the number of follicles observed, oocytes retrieved, and embryos obtained, as well as implantation rates, were significantly higher (P < 0.001) in the long protocols than in the short ones.
Results: Pregnancy rates were similar in all groups, although a trend for better results was observed in buserelin-long compared to buserelin-short. There were no differences in the results achieved with buserelin or leuprolide.
Conclusion: The administration of GnRH analogues (buserelin and leuprolide acetate) in long protocols induced a more intense ovarian response and was associated with significantly higher implantation rates and also a trend for higher pregnancy rates, although this difference was not statistically significant.