Advantages of GnRH antagonists over the agonists in IVF

Dafopoulos KC, Messinis IE

Department of Obstetrics and Gynecology, University of Thessaly, Larissa, Greece

Correspondence: Dafopoulos Konstantinos, Department of Obstetrics and Gynecology, University of Thessaly, Larissa University hospital, GR-41110, Larissa, Greece

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GnRH antagonists were introduced in IVF in the late 1990s. They are effective in reliable prevention of premature LH surge and luteinization during superovulation and their safety is well documented. Two different antagonist protocols have been developed: the multiple dose protocol and the single dose protocol. GnRH antagonists have many advantages compared to agonists. Duration of GnRH antagonist treatment, amount of gonadotrophins and duration of stimulation are decreased when antagonist protocols are used. Furthermore, there are no estrogen deprivation symptoms or ovarian cyst formation, i.e. conditions that are related to pituitary down regulation and flare up effect of agonists. Consequently, antagonists are better tolerated by patients. There is no risk to administer the antagonists during the early pregnancy as might occur with the long mid-luteal agonist protocol. Furthermore, the occurrence of severe ovarian hyperstimulation syndrome is reduced. Antagonists might improve the outcome in poor responders and they are appropriate for development of "softer" IVF protocols.

Key words: GnRH antagonists; GnRH agonists; IVF; advantages