Comparion of the Outcomes Between Vitrification and Slow-Freezing Methods for Cryopreservation of Embryos in Cleavage Stage

Objective: To compare the outcomes of vitrification and slow-freezing methods for cryopreservation of cleavage stage embryos in assisted reproductive technology.Methods: A retrospective statistical analysis was performed in our center on 577 vitrification cycles and 276 slow-freezing cycles.The embryo survival and intact survical rate after embryo recovery,embryo implantation rate and clinical pregnancy rate and other indicators were compared.Results: In rapid freezing group,the numbers of embryos thawed each cycle were less than in the slow-freezing group,but the numbers of survival embryos were more,and the period recurrence rate was higher.Vitrified embryos was superior to the procedural slowly-frozen embryos in embryo survival rate,intact embryo survival rate,embryo implantation rate,clinical pregnant rate,and transfer cancel rate(all P0.05).Conclusion: Vitrification is better to preserve the potential development of frozed embryo after recovery,and is an ideal method for cryopreservation of the cleavage embryos.