The Effectiveness of the GnRH Agonist/Antagonist Protocols for Different Poseidon Subgroups of Poor Ovarian Responders

<b>Background/Objectives:</b> Poor responder patients represent the greatest challenge in ART. An inadequate response to COS strongly correlates with a reduced chance of conception. A novel classification of poor responders overcame a deficiency in the Bologna criteria and distinguished an expected and unexpected low ovarian response, allowing for an individual treatment approach to be created. In this study, we compared the clinical outcomes in poor responders, according to two different ovarian stimulation protocols, GnRH agonists and antagonists, classified according to the Poseidon criteria, to determine the most effective protocol for each group. <b>Methods:</b> This retrospective study involved 1323 low-prognosis women ranked according to the Poseidon classification and a control group of normal responders. <b>Results:</b> The GnRH-antagonist protocol showed some advantage in the Poseidon 1b group whereas the GnRH-agonist protocol was more effective in the Poseidon 4 group. There were no differences in live births or miscarriage rates in poor responders among these two protocols. <b>Conclusions:</b> Using both the agonist/antagonist approaches, live birth rates are two or even three times less in Poseidon patients in comparison to normal responders. The number of obtained oocytes, their maturity and quality, and women's ages were found to be the most influential determinants for a successful outcome. Further investigations into ovarian stimulation strategies are required to enhance oocyte number and live birth occurrence.