This prospective and randomized study was performed to evaluate whether the replacement of GnRH agonist by a GnRH antagonist in oocyte donation recipients during endometrial preparation has any impact on pregnancy and implantation rates.

This was a prospective and randomized study undertaken between January 2004 and December 2007. One hundred patients with an indication for oocyte donation with functioning ovaries and IVF with or without intracytoplasmatic sperm injection (ICSI) were recruited for the study. After assignment to IVF or IVF/ICSI randomization was performed to 1 of the 2 treatment groups (GnRH agonist or GnRH antagonist during endometrial preparation in oocyte donation recipients) using a computed-generated randomization schedule assigned via numbered sealed envelopes. In our program, we used excess oocytes from IVF that were voluntarily donated by patients after informed consent. The indications for oocyte donation were reduced ovarian reserve (59%), recurrent IVF failures (21%), premature ovarian failure (16%), and genetic anomaly (4%). This study was performed according to the declaration of Helsinki and the European Community note on Good Clinical Practice for trials on medical products in the European Community (CPMP Working Party on Efficacy of Medical Products, 1990). Furthermore, the local ethics committee approved the study protocol, and written informed consent was obtained from all patients.