This chapter reviews the dynamics of the endometrial transition from the non-receptive stage to the receptive stage at the proteomic level. The application of proteomics technology to the endometrium can be used to search for new biomarkers to determine endometrial receptivity and possible causes of infertility and to investigate interceptive molecules to prevent embryo implantation. An in-depth investigation of the human proteome is vital to understand the cellular function and to comprehend biological processes and/or disease states. Technological advances in translational research have enabled the non-invasive determination of the proteomic/secretomic status of an embryo. Discriminating secretome signatures between individual euploid and aneuploid blastocysts has also been addressed. Microdrops of the spent in vitro fertilization (IVF) culture medium from individual blastocysts of transferable quality were processed and analyzed by surface-enhanced laser desorption and ionization time-of-flight mass spectrometry (SELDITOF/MS) to determine a blastocyst secretome fingerprint.