Outcome of Frozen-Thawed Embryo Transfer Derived from Gonadotropin Releasing Hormone Antagonist Cetrorelix or Ganirelix Cycle

Introduction: GnRH antagonist activates GnRH receptors localized on the reproductive tract. In fresh antagonist cycle it could decrease the synthesis of growth factors, compromising the mitotic program of granulose and endometrial cells and potentially influencing fertilization mechanism and zygote development. Outcomes of frozen-thawed embryos after GnRH antagonist treatment have been studied by comparison to embryos derived from long GnRH agonist protocol and there are no studies comparing outcomes after treatment with cetrorelix versus ganirelix.

Aim: to compare outcome after frozen-thawed embryo transfer following controlled ovarian hyperstimulation (COH) cycle using GnRH antagonist cetrorelix or ganirelix.

Materials and Methods: a retrospective study collecting data of 157 frozen-thawed embryo transfer cycles following antagonist treatment during 2014-2015. Complete data for analysis was collected form 127 cycles, 57 derived from a cycle using cetrorelix and 70 using ganirelix. Demographic data including age, gravity, parity, BMI and day 3 FSH were compared between the groups. The primary outcome of the study was live-birth rate. Implantation rate and clinical pregnancy rate were calculated as well. Statistical analysis was done using the student t test to compare normally distributed variables and the Fisher`s test.

Results: the groups were comparable as there were no significant differences in the demographic data including average age, gravity and parity, BMI and day 3, baseline FSH levels. Oocyte retrieval results demonstrated no significant difference in the number of oocytes retrieved, number of 2PN and number day 3 and 5 embryos transferred. Comparing the two groups, differences in implantation rate, clinical pregnancy rate or live birth rate did not reach statistical significance.

Conclusions: use of both GnRH antagonists are comparable regarding the clinical outcome after frozen–thawed embryos transfer implying that oocyte quality is not affected by the specific type of GnRH antagonist. Further larger studies are warranted to confirm our findings.