title: Predictive value of embryo grading for embryos with known outcomes.
abstract: OBJECTIVE
  To compare pronuclear morphology (Z-score), day 3 embryo grade, and day 3 cell number in the prediction of successful implantation rates (IRs), including cycles in which all or none of the embryos implanted.
  
  
  METHODS
  Retrospective analysis.
  
  
  METHODS
  University-based IVF center.
  
  
  METHODS
  Four hundred twenty-six fresh IVF day 3 transfers of 852 embryos in women <36 years of age from January 2000 to December 2003 in whom all or none of the embryos implanted.
  
  
  METHODS
  Evaluation of Z-scores, embryo morphology, cell number, and IR.
  
  
  RESULTS
  Day 3 parameters were more predictive than Z-scores. When early parameters were poor (Z-score) but late parameters were both good, the IR was 38%, compared with 4% when the Z-score was good but the late parameters were poor.
  
  
  CONCLUSIONS
  Embryo grading systems are useful in the prediction of embryo implantation. In particular, cell number and embryo grade are more predictive than Z-scores. Therefore, late parameters have a better prognostic value than Z-scores when selecting embryos for transfer.
authors.affiliation: Center for Advanced Reproductive Services, University of Connecticut School of Medicine, Department of Obstetrics and Gynecology, Farmington, Connecticut, USA.
authors.forename: Vanessa N
authors.initials: VN
authors.lastname: Weitzman
authors.forename: Jennifer
authors.initials: J
authors.lastname: Schnee-Riesz
authors.forename: Claudio
authors.initials: C
authors.lastname: Benadiva
authors.forename: John
authors.initials: J
authors.lastname: Nulsen
authors.forename: Linda
authors.initials: L
authors.lastname: Siano
authors.forename: Donald
authors.initials: D
authors.lastname: Maier
mesh_terms: D000328:Adult; D002455:Cell Division; D010064:Embryo Implantation / Q000502:physiology*; D004622:Embryo, Mammalian / Q000166:cytology / Q000502:physiology*; D047108:Embryonic Development / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro / Q000706:statistics & numerical data; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D012189:Retrospective Studies