title: [Comparison of clinical outcomes of blastocysts derived from non-top quality embryos and cleavage-stage high-quality embryos in frozen-thawed embryo transfer cycles].
abstract: OBJECTIVE
  To explore the developmental potential of embryos at different developmental days and provide evidence for blastocyst culture of non-top quality cleavage stage embryos in frozen-thawed embryo transfer (FET) cycles.
  
  
  METHODS
  The clinical data of 687 FET cycles were retrospectively analyzed. According to the embryo freezing time, the patients were divided into day 5 (D5) blastocyst group (n=87), day 6 (D6) blastocyst group (n=111) and day 3 cleavage-stage embryo (D3) group (n=489) with hormone replacement cycles or natural cycles for endometrial preparation. The clinical pregnancy rates, miscarriage rates, and implantation rates were compared between the 3 groups.
  
  
  RESULTS
  The clinical pregnancy rate, miscarriage rate and implantation rate per transfer were 58.6%, 9.8%, and 42.9% in D5 group, 32.4%, 19.4%, and 23.3% in D6 group, and 44.9%, 16.4%, and 26.9% in D3 group, respectively. The clinical pregnancy rate and implantation rate were significantly higher in D5 group than in the other two groups (P<0.05).
  
  
  CONCLUSIONS
  The D5 blastocysts derived from non-top quality D3 embryos after cryopreservation can have better clinical outcomes than those derived from D3 cleavage-stage embryos and D6 blastocysts, and are therefore a better option than D3 cleavage-stage embryos in FET cycles.
authors.affiliation: Reproductive Medicine Center, Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. E-mail: zhiduoxinrun@163.com.
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Xu
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.forename: Xiao-Long
authors.initials: XL
authors.lastname: Tian
authors.forename: Yu-Dong
authors.initials: YD
authors.lastname: Liu
authors.forename: Nan
authors.initials: N
authors.lastname: Wang
authors.forename: De-Sheng
authors.initials: DS
authors.lastname: Ye
authors.forename: Ping-Ping
authors.initials: PP
authors.lastname: Guo
authors.forename: Shi-Ling
authors.initials: SL
authors.lastname: Chen
mesh_terms: D000022:Abortion, Spontaneous; D001755:Blastocyst; D002970:Cleavage Stage, Ovum; D015925:Cryopreservation; D010064:Embryo Implantation; D004624:Embryo Transfer; D005260:Female; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies