Embryo implantation and GnRH antagonists - Ovarian actions of GnRH antagonists

The gonadotrophin-releasing hormone (GnRH) antagonists, cetrorelix and gani relix, have both been approved for ovarian stimulation to prevent a prematu re LH surge. Since GnRH receptors and their gene expression have been detec ted in human ovary, concern has risen over whether GnRH antagonists might a ffect ovarian function. Three large trials which compared GnRH agonists (us ed in the standard protocol worldwide), with the new antagonist treatment f ound no significant differences concerning the most important goals, e.g, p regnancy rate, fertilization and quality of oocytes, However, the concentra tion of oestradiol, and the pregnancy and implantation rates were Lower in GnRH antagonist-treated patients. These findings again fuelled the debate a bout the possible extrapituitary effects of GnRH antagonists. Here, we revi ew the conflicting data in the literature on the ovarian effects of GnRH an tagonists and discuss our own results, In our view, it is unlikely that GnR H antagonists have a relevant impact on ovarian steroidogenesis and functio n; however, GnRH antagonists may exert other effects on the ovary.