Impact of embryo factors on clinical outcome in frozen-thawed embryo transfer cycles

Objective:To investigate the influence of post-thaw survival rate or pre-freeze embryo qulity and clinical pregnancy rate in frozen-thawed embryo transfer program(FET).Methods: A total of 683 FET of the patients aged 35 years and who were only transferred 2 embryos in a cycle were analyzed retrospectively from Jan 2008 to Dec 2010.Cases were divided into 4 groups according to the pre-freeze embryo qulity and post-thaw survival rate(Group A: fully intact embryos and ≥1 pre-freeze high-qulity embryo,Group B: fully intact embryos and no pre-freeze high-qulity embryo,Group C: post-thaw damaged embryos and ≥1 pre-freeze high-qulity embryo,Group D: post-thaw damaged embryos and no pre-freeze high-qulity embryo).And clinical pregnancy rate and multiple pregnancy rate were compared between groups.Results: There was no significant difference in the clinical pregnancy rate and multiple pregnancy rate between Group A and Group C,or Group B and Group D,or Group A+B and Group C+D.But there was a significantly higher pregnancy rate in Group A and Group C(A vs.B,A vs.D,A+C vs.B+D,P0.01;C vs.B,P0.05).Conclusions: If there was any pre-freeze high-qulity embryo in the post-thaw embyos,they will have a higher pregnancy rate.