Huang P, et al. - This retrospective analysis was carried out to determine the impacts of the intrauterine perfusion of hCG before a frozen-thawed embryo transfer (FET) in women with different implantation failure numbers. Decreased pregnancy rates were observed with the number of transplant failures. Significantly improved pregnancy rates were reported as a consequence of intrauterine administration of hCG before FET, this was noted especially after one and three or more implantation failures.