title: Limited value of morphological assessment at days 1 and 2 to predict blastocyst development potential: a prospective study based on 4042 embryos.
abstract: BACKGROUND
  Non-invasive and routine developmental markers are available to select the most viable embryo; however their respective values in terms of blastocyst development potential remain difficult to distinguish.
  
  
  METHODS
  During this prospective study, the sequential growth of 4042 embryos individually cultured from day 1 to day 5/6 was recorded. Pronuclear morphology on day 1, and early cleavage, cell number and fragmentation rate on day 2 were evaluated for each zygote. Additionally, blastocyst transfers were analysed with regard to their implantation ability and early embryo development parameters.
  
  
  RESULTS
  Once adjusted to each other, each of the four parameters remained related to blastocyst development. Early cleavage and cell number on day 2 were the most powerful parameters to predict the development of a good morphology blastocyst at day 5. Moreover, whereas transfers of a good morphology blastocyst were associated with high implantation and live birth rates, parameters of early development were not helpful in predicting their implantation ability.
  
  
  CONCLUSIONS
  The combination of all four parameters allowed the prediction of blastocyst development with an area under the receiver operating characteristics curve of 0.688, which represents a fairly low prediction of embryo viability. Such results indicate that it is necessary to search for additional criteria, including the ability of the blastocyst to develop.
authors.affiliation: Service de Médecine et Biologie de la Reproduction, CHU Bretonneau, 2 Boulevard Tonnelle, 37000 Tours, France.
authors.forename: F
authors.initials: F
authors.lastname: Guerif
authors.forename: A
authors.initials: A
authors.lastname: Le Gouge
authors.forename: B
authors.initials: B
authors.lastname: Giraudeau
authors.forename: J
authors.initials: J
authors.lastname: Poindron
authors.forename: R
authors.initials: R
authors.lastname: Bidault
authors.forename: O
authors.initials: O
authors.lastname: Gasnier
authors.forename: D
authors.initials: D
authors.lastname: Royere
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000166:cytology*; D002467:Cell Nucleus / Q000378:metabolism; D015331:Cohort Studies; D046149:Embryo Culture Techniques; D010064:Embryo Implantation; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000473:pathology*; D047108:Embryonic Development; D005260:Female; D006801:Humans; D015999:Multivariate Analysis; D011247:Pregnancy; D011446:Prospective Studies; D015053:Zygote