GnRH agonists or antagonists in ovarian stimulation

Loutradis D, Stefanidis K, Antsaklis A, Michalas S

First Department of Obstetrics and Gynecology, University of Athens, Alexandra hospital, Athens, Greece

Correspondence: Stefanidis K, 152 Michalakopoulou St, GR-11527, Athens, Greece. E-mail:


Ovarian stimulation is an important step in the success rate of in vitro fertilization (IVF) allowing multiple follicular growth and oocytes retrieval, and, consequently, more embryos. Blockade of pituitary gonadotrophin secretion occurs upon desensitization when a continuous GnRH stimulus is provided by means of an agonist or when pituitary receptors are occupied with a competitive antagonist. GnRH analogs prevent premature luteinization. Four protocols have been designed for assisted reproduction technology (ART) treatment, long protocol and short protocol with GnRH agonist and multiple-dose protocol and single-dose with an antagonist. A review of GnRH analogs applications in ART cycles are presented. Long protocol with GnRH agonist is the best protocol regarding to pregnancy rate. Smaller doses of gonadotrophins, shorter stimulation period and lower ovarian hyperstimulation syndrome (OHSS) incidence are reported in literature using GnRH antagonist compared to agonist.

Keywords: GnRH agonists, GnRH antagonists, IVF

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