Hormonal induction of endometrial receptivity

Objective: To review and synthesize information from the scientific literature pertaining to the hormonal induction of endometrial receptivity before ET. Design: Critical review of selected scientific literature, synthesis and formulation of opinion. Setting: Not 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 E-2 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 E-2 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. (Fertil Steril (R) 2011;96:530-5. (C) 2011 by American Society for Reproductive Medicine.)