Pirtea P, De Ziegler D, Tao X, et al. - The true prevalence of recurrent implantation failure was investigated via performing a retrospective cohort study of women (n = 4,429) with anatomically normal uterus who underwent up to three consecutive frozen euploid single embryo transfers (FE-SETs). The first, second, and third FE-SET had sustained implantation rates of 69.9%, 59.8%, and 60.3% per transfer, respectively. Observations revealed a rare occurrence of true recurrent implantation failure. Among those patients with the ability to make euploid blastocysts, failure to attain a clinical pregnancy with three embryos transferred would occur in < 5%. Further investigation is recommended to determine whether this threshold identifies a truly recalcitrant group or simply a statistical certainty based on random variation.