title: Prediction of clinical pregnancy in vitrified-warmed single blastocyst transfer cycles by pre-freeze morphology.
abstract: BACKGROUND
  The selection of blastocyst warmed for transfer is based on pre-freeze morphology in vitrified-warmed single blastocyst transfer cycles. But, it is controversial which parameter of blastocyst morphology most closely related to the clinical outcomes.
  
  
  OBJECTIVE
  To estimate the effect of blastocoele expansion, trophectoderm (TE) morphology grade, and inner cell mass (ICM) morphology grade on clinical pregnancy in vitrified-warmed single blastocyst transfers.
  
  
  METHODS
  There were 172 vitrified-warmed single blastocyst transfer cycles during the year 2012 included in this analysis. Comparison of clinical results between pregnancy and no pregnancy group based on patient and blastocyst morphology characteristics was done. Then stepwise logistic regression analysis was used to select the best morphological predictor for clinical pregnancy. Last, comparison of patient characteristics and clinical outcomes separated by the best independent morphological predictor was done.
  
  
  RESULTS
  Comparison of clinical results between pregnancy and no pregnancy group and logistic regression showed the clinical pregnancy rate was affected by ICM. Comparison of patient characteristics separated by ICM grade, ICM grade A cycles got higher clinical pregnancy rate than ICM grade B cycles (54.3% vs. 35.0% respectively, p=0.037).
  
  
  CONCLUSIONS
  Blastocyst with good ICM morphology could increase clinical pregnancy rate in vitrified-warmed single blastocyst transfer cycles.
authors.affiliation: Department of Reproductive Medical Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Reproductive Medical Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Reproductive Medical Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Reproductive Medical Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Department of Reproductive Medical Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
authors.forename: Shiquan
authors.initials: S
authors.lastname: Xiao
authors.affiliation: Department of Reproductive Medical Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
authors.forename: Yonggen
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Reproductive Medical Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
authors.forename: Haiqing
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Reproductive Medical Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Huang
keywords: Blastocyst; In vitro fertilization; Innercellmass; Morphology; Vitrification