title: GnRH agonist versus GnRH antagonist in in vitro fertilization and embryo transfer (IVF/ET).
abstract: Several protocols are actually available for in Vitro Fertilization and Embryo Transfer. The review summarizes the main differences and the clinic characteristics of the protocols in use with GnRH agonists and GnRH antagonists by emphasizing the major outcomes and hormonal changes associated with each protocol. The majority of randomized clinical trials clearly shows that in "in Vitro" Fertilization and Embryo Transfer, the combination of exogenous Gonadotropin plus a Gonadotropin Releasing Hormone (GnRH) agonist, which is able to suppress pituitary FSH and LH secretion, is associated with increased pregnancy rate as compared with the use of gonadotropins without a GnRH agonist. Protocols with GnRH antagonists are effective in preventing a premature rise of LH and induce a shorter and more cost-effective ovarian stimulation compared to the long agonist protocol. However, a different synchronization of follicular recruitment and growth occurs with GnRH agonists than with GnRH antagonists. Future developments have to be focused on timing of the administration of GnRH antagonists, by giving a great attention to new strategies of stimulation in patients in which radio-chemotherapy cycles are needed.
authors.affiliation: Unit of Physiopathology of Human Reproduction and Gametes Cryopreservation, Department of Gynecology, Obstetric and Neonatolgy, University of Bari "Aldo Moro", Bari, Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Depalo
authors.forename: K
authors.initials: K
authors.lastname: Jayakrishan
authors.forename: Gabriella
authors.initials: G
authors.lastname: Garruti
authors.forename: Ilaria
authors.initials: I
authors.lastname: Totaro
authors.forename: Mariantonietta
authors.initials: M
authors.lastname: Panzarino
authors.forename: Francesco
authors.initials: F
authors.lastname: Giorgino
authors.forename: Luigi E
authors.initials: LE
authors.lastname: Selvaggi
mesh_terms: D000367:Age Factors; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D005498:Follicular Phase / Q000187:drug effects; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000819:agonists* / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors*; D006801:Humans; D008183:Luteal Phase / Q000187:drug effects; D007986:Luteinizing Hormone / Q000378:metabolism; D015201:Meta-Analysis as Topic; D016471:Ovarian Hyperstimulation Syndrome / Q000517:prevention & control; D010062:Ovulation Induction / Q000379:methods; D011247:Pregnancy; D018873:Pregnancy Rate; D016032:Randomized Controlled Trials as Topic
chemical_list: D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; C062876:cetrorelix