Hafezi M, et al. - Researchers sought to determine the influence of intrauterine human chorionic gonadotropin (hCG) before embryo transfer on the clinical pregnancy and live birth rates after vitrified-warmed embryo transfer (ET) in programmed cycles. They conducted a single-blind randomized clinical trial for eligible patients underwent frozen ET cycles with long-term hormonal GnRH agonist protocol for endometrial preparation. In this work, intrauterine injection of 500 IU hCG before vitrified-warmed ET at cleavage stage was observed having no beneficial effect on pregnancy outcome and was thus not suggested.