title: A study to determine if embryo cryopreservation influences the potential of rapidly growing embryos to successfully implant in uterine environments not influenced by controlled ovarian hyperstimulation.
abstract: OBJECTIVE
  To determine if transferring at least one embryo with eight blastomeres at 72 hours improves prognosis of donor oocyte recipients. The study aim was to verify if cryopreservation increases or decreases the advantage of rapidly growing embryos. The study could exclude the influence of controlled ovarian hyperstimulation (COH) on the uterine environment.
  
  
  METHODS
  All transfers, fresh or frozen, using exclusively embryos that resulted from fertilization of donor oocytes over a three-year period were evaluated.
  
  
  RESULTS
  Significantly higher pregnancy rates (PRs) and delivery rates were found in donor oocyte recipients receiving at least one eight-cell embryo compared to transfers without any eight-cell embryos. These differences were not found when comparing frozen embryo transfers (ETs). The data could not be explained by confounding variables.
  
  
  CONCLUSIONS
  The inclusion of at least one 8-cell embryo on day 3 fresh ET resulted in higher PRs even without the influence of COH. However, higher blastomere number did not influence frozen ET outcome.
authors.affiliation: The University of Medicine and Dentistry of New Jersey Robert Wood Johnson Medical School at Camden, Cooper Hospital/Univerity Medical Center, Department of Obstetrics and Gynecology New Jersey, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Check
authors.forename: D
authors.initials: D
authors.lastname: Kiefer
authors.forename: D
authors.initials: D
authors.lastname: Summers-Chase
authors.forename: M
authors.initials: M
authors.lastname: Check
authors.forename: J K
authors.initials: JK
authors.lastname: Choe
mesh_terms: D001757:Blastomeres; D015925:Cryopreservation; D010064:Embryo Implantation; D004624:Embryo Transfer; D006801:Humans