Hormonal induction of endometrial receptivity

ObjectiveTo review and synthesize information from the scientific literature pertaining to the hormonal induction of endometrial receptivity before ET.DesignCritical review of selected scientific literature, synthesis and formulation of opinion.SettingNot applicable.Patient(s)Prospective recipients of oocyte donation or candidates for frozen embryo transfer.Intervention(s)Hormonal treatment for the purpose of induction of endometrial receptivity.Main Outcome Measure(s)Successful induction of endometrial receptivity, as substantiated by live birth rates, pregnancy rates, implantation rates or by measuring putative markers of endometrial receptivity.Result(s)The practice of assisted reproductive technology, particularly third-party parenting, in which the source of oocytes is separated from the endometrium, has allowed a separate assessment of embryo and endometrial development. Endometrial receptivity can be induced by exogenously administered E2 and P in a variety of regimens. The degree of synchrony between embryo and endometrium influences the probability of embryo implantation and may be controlled by initiating P stimulation at different times relative to the stage of embryo development. Many substances have been investigated as adjuncts to E2 and P in the induction of endometrial receptivity, but at the present time, their value is unproven.Conclusion(s)Estrogen and P are the only hormones necessary to prepare the endometrium for implantation.