Kuroda K, Matsumura Y, Ikemoto Y, et al. - Researchers sought to report on the pregnancy outcomes after the OPtimization of Thyroid function, Immunity, and Uterine Milieu (OPTIMUM) treatment strategy in patients with repeated implantation failure (RIF). Implantation testing, including a hysteroscopy, endometrial biopsy for CD138 immunostaining and bacterial culture, and serum 25‐hydroxyvitamin D3, interferon‐γ‐producing helper T (Th1) cell, IL‐4‐producing helper T (Th2) cell, thyroid‐stimulating hormone, thyroid peroxidase antibody, and thrombophilia screening were performed on infertile women with a history of RIF after more than three embryo transfer (ET) cycles between April 2017 and August 2018. They performed treatment of chronic endometritis with antibiotics, aberrant high Th1/Th2 cell ratios with vitamin D and/or tacrolimus intake, overt/subclinical hypothyroidism with levothyroxine, and thrombophilia with low‐dose aspirin. Of the 116 RIF women, they recruited 88 women with 133 ET cycles from a questionnaire‐based survey concerning pregnancy outcomes. In addition, they recruited 59 consecutive RIF patients without the OPTIMUM treatment strategy as a control. They observed significantly higher pregnancy outcomes in the OPTIMUM group vs those in the control. The OPTIMUM treatment strategy was thus suggested as effective in improving pregnancy outcomes in patients with RIF.