Embryo implantation?? is a complex process requiring synchrony between a healthy embryo and a functionally competent or receptive endometrium. Endometrial receptivity is the ability of the uterine lining to permit attachment and invasion of the blastocyst. The endometrial receptivity analysis uses Next Generation Sequencing to assess the gene expression in order to classify the endometrium as receptive or non-receptive and to identify the personalized (Window of Implantation) WOI, advising an adjusted progesterone duration in a subsequent cycle for those found to have non-receptive endometrium.