MIF and Infertility: 30 infertile women with multiple implantation failures (MIF) and a fertile control group were studied. Researchers obtained endometrial biopsies in the proliferative phase and measured expression of LIF using immunohistochemistry and western blotting. Lower expression of LIF was found in infertile women with MIF compared to fertile women. They determined that initial lower expression of LIF during the proliferative phase may be a cause of multiple failures of implantation.