Nakagawa K, et al. - In this prospective observational study, researchers investigated whether treatment with tacrolimus is safe for women with repeated implantation failures (RIF) or recurrent pregnancy losses (RPL) undergoing assisted reproductive technology cycles as well as for their babies. The women included in this study exhibited elevated peripheral blood Th1/Th2 (CD4⁺IFN-γ⁺/CD4⁺IL-4⁺) cell ratios (≥10.3). Both before and during pregnancy (1-4 mg/d), tacrolimus was received by the participants. All women delivered a live-born infant(s). From 109 women, 113 babies were born, including four twin pregnancies. Findings revealed no association of tacrolimus treatment with obstetrical and perinatal complications in women with RIF and RPL.