Artificial reproductive technologies (ART) have rapidly evolved over the past decades in order to improve the reproductive outcomes of infertile couples, including great advances in the cryopreservation process, as well as in the field of Preimplantational Genetic Testing for Aneuploidies (PGT-A). Although endometrial preparation for frozen embryo transfer (FET) can be accomplished in a natural, natural-modified or an artificial cycle, artificial endometrial preparation allows an easier programming of the embryo transfer (ET), and thus is frequently the preferred strategy by clinicians. The timing of endometrial receptivity is brief and failure of the endometrium to achieve a receptive state is thought to be a key factor for infertility and a major challenge for most reproductive medical clinicians. Endometrial receptivity seems to be driven by time of progesterone (P) exposure, only after sufficient exposure to estrogen and therefore P is absolutely necessary for embryo implantation and the maintenance of pregnancy.