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.
Highlights
Several protocols are available for in Vitro Fertilization and Embryo Transfer
This study showed that there was no significant difference following GnRh ant compared with GnRh agonist regimensin the live birth rate and in the ongoing pregnancy rate per woman randomized (OR = 0.88, 95% CI = 0.77 to 1.00, P = 0.05)
We emphasize what has been suggested by Griesinger, that, “Perhaps Gonadotropin Releasing Hormone (GnRH) antagonist is used as drug of second choice in IVF practice?” This Author, evaluating the data from the Germany IVF registry and stratifying the results by cycles rank, observed that the proportion of GnRH-ant cycles increases from 23% in first treatment to 35% in fifth treatment and to 48% in tenth treatment
Summary
GnRH-ant regimen is effective in preventing a premature rise of LH and results in a shorter and more cost-effective ovarian stimulation protocol compared to the long agonist protocol. The effect of elevated LH levels in follicular phase before GnRH-ant administration, has to be focused on. An optimization of the currently used stimulation protocol is needed with regard to timing of GnRH-ant administration, taking into account strategies for mild ovarian stimulation, making more patient friendly IVF protocols for patients who have to initiate radio-chemotherapy procedures. Several aspects of the GnRH-ant use needs to be further explored such as the direct effects of GnRHant on extra-pituitary tissues (i.e., corpus luteum, endometrium, ovary, embryo), and potential pharmacological differences among the existing compounds. All authors have read and approved the final manuscript
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