Comparison of cryopreservation outcome with gonadotropin-releasing hormone agonists or antagonists in the collecting cycle

Objective: To compare the pregnancy rates of frozen-thawed 2-pronucleate (2PN) oocytes obtained either in a long protocol or in an antagonist protocol and ovarian stimulation with either human menopausal gonadotropin (hMG) or recombinant follicular stimulating hormone (recFSH). Design: Retrospective data analysis. Setting: Academic infertility center. Patient(s): Three hundred forty-two infertile couples who underwent a transfer of cryopreserved 2PN oocytes. Intervention(s): Hmg (n = 194) or recFSH (n = 92) in a long protocol or hMG (n = 16) or recFSH (n = 40) stimulation under pituitary suppression with the GnRH antagonist Cetrotide was used. The 2PN oocytes were transferred after endometrial preparation using E₂ valerate and vaginal progesterone (Crinone 8% vaginal gel). Main Outcome Measure(s): Implantation, pregnancy, and abortion rates. Result(s): Implantation rates in the freeze-thaw cycles were 5.6% (hMG) and 3.8% (recFSH) with 2PN oocytes from the long protocol and 7% from the antagonist cycles, irrespective of whether hMG or recFSH was used. Pregnancy rates were similar independent of whether they resulted from the long-protocol cycles with hMG (15.4%) and recFSH (13.1%) or from the antagonist protocol cycles with hMG (25.0%) and recFSH (17.5%). Conclusion(s): The potential to implant is independent of the gonadotropin-releasing hormone analogue and gonadotropin chosen for the collection cycle when previously cryopreserved 2PN oocytes were replaced after thawing in the cleavage stage.