Effect of embryo factors on clinical outcome of frozen-thawed embryo transfer

Objective: To explore the effect of embryo factors on post-thaw embryo survival rate and clinical pregnancy rate in frozen-thawed embryo transfer(FET) cycles.Methods:The clinical data of 149 cycles of FET were retrospectively analyzed.Groups were divided according to pre-freeze embryonic developmental stage,pre-freeze embryo quality and blastomere survival rates,respectively,and embryo survival rates and/or clinical pregnancy rates were compared among these groups.Results:There was no significant difference in the embryo survival rate and clinical pregnancy rates between embryos frozen on the 2 nd day of fertilization and those frozen on the 3rd day(P0.05).The clinical pregnancy and implantation rates of high quality pre-freeze embryo were significantly higher than that of low quality pre-freeze embryo(P0.05).The clinical pregnancy and implantation rates of transferred embryos with fully intact blastomere and with mixed embryos were significantly higher than that with partially damaged embryos(P0.05).Conclusion:Pre-freeze embryo quality and blastomere survival status of post-thaw embryos were important factors influencing clinical outcome in FET cycles.