We make use of the measurement of changing numbers, distribution, and clustering of immune cells in endometrium, as well as the interaction of different pairs of immune cells as an innovative and comprehensive test (EndoTest) to predict successful implantation. EndoTest analyzes the immune cell profile in endometrium before natural and artificial conception to predict successful implantation. This introduces a novel perspective to improve implantation and clinical pregnancy outcomes after conception, which may throw light upon the measurement of endometrial receptivity and adaptation.