32 women with unexplained infertility and 17 fertile women were studied. Endometrial biopsy samples were obtained and studied using a sensitive enzyme-linked immunosorbent assay (ELISA). LIF secretion was 2.2 times higher during the secretory phase than proliferative phase in fertile women whereas infertile women did not have this elevation in cytokine production. They concluded that the deregulation of endometrial LIF secretion may be linked to unexplained infertility and repetitive failures of implantation. Here, LIF is linked to Infertility.