Objective: To evaluate whether oocyte quality, implantation and pregnancy rates in intra-cytoplasmic sperm injection (ICSI) cycles are related to the duration of gonadotrophin-releasing hormone antagonist (GnRH-ant) use.

Material and Method: A total of 138 patients who were treated with GnRH-ant protocol at the IVF Clinic from March 2010 to January 2012 were enrolled in this study. The patients were classified into three groups according to duration of GnRH-ant use. Group 1: 4 days (n=51); group 2:5 days (n=57); group 3:6 days (n=30) antagonist application. Main outcome measures were implantation rate, pregnancy rate, fertilization rate, number of oocytes retrieved (NOR), number of mature oocytes (NMO).

Results: The NOR and NMO were the lowest in group 1, intermediate in group 2, and the highest in group 3 respectively. There is no statistically significant difference between the groups in regard to total gonadotrophins used, fertilization, implantation or pregnancy rates. The pregnancy rates per ET and cycle were 37.9% and 31.8%, respectively.

Conclusion: We noticed that longer GnRH-ant use was associated with more oocytes retrieved and more mature oocytes, but no difference in fertilization, implantation or pregnancy rates concluding that longer GnRH-ant use does not have a detrimental effect on in vitro fertilization outcome.