title: Transferring two grades I cleavage-stage embryo might not be a good protocol.
abstract: OBJECTIVE
  The aim of this study was to explore whether transferring two grades I cleavage-stage embryo was suitable for the patients in the first fresh transfer.
  
  
  METHODS
  This study included 202 single grades I cleavage-stage, 229 single grades III cleavage-stage, 743 single excellent blastocyst, 522 double grades I cleavage-stage, and 596 double grades III cleavage-stage embryo transfers. Main clinical outcomes: clinical pregnancy and twin-pregnancy rate.
  
  
  RESULTS
  Among single excellent blastocyst, single grades I and single grades III group, the clinical pregnancy rate was significantly higher in single excellent blastocyst group than single grades I and grades III group (67.16% versus 42.08% versus 23.97%; p < 0.001). When transferred double grades I cleavage-stage embryos, the clinical pregnancy rate reached 68.20% which was no significant difference compared with the single excellent blastocyst group (67.16%). However, the twin-pregnancy rate was significantly higher in double grades I group than double grades III and single excellent blastocyst group (43.26% versus 26.70% versus 0.60%; p < 0.001).
  
  
  CONCLUSIONS
  Because of higher twin-pregnancy incidence rate, transferring two grades I cleavage-stage embryo might not be a good protocol. Extended culture to blastocyst-stage could be considered for the patient with only two grades I cleavage-stage embryos.
authors.affiliation: a The ART Center, Northwest Women's and Children's Hospital , Xi'an , China.
authors.forename: Mingzhao
authors.initials: M
authors.lastname: Li
authors.affiliation: a The ART Center, Northwest Women's and Children's Hospital , Xi'an , China.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: a The ART Center, Northwest Women's and Children's Hospital , Xi'an , China.
authors.forename: Chun
authors.initials: C
authors.lastname: Ma
authors.affiliation: a The ART Center, Northwest Women's and Children's Hospital , Xi'an , China.
authors.forename: Juanzi
authors.initials: J
authors.lastname: Shi
mesh_terms: D000328:Adult; D002970:Cleavage Stage, Ovum; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies
keywords: Cleavage-stage; blastocyst-stage; clinical pregnancy