title: Assessment of early cleaving in vitro fertilized human embryos at the 2-cell stage before transfer improves embryo selection.
abstract: OBJECTIVE
  To determine the most viable embryos for transfer.
  
  
  METHODS
  Study 1: Preselection of early-cleaving 2-cell embryos for transfer. Study 2: Alternating weeks during which preselection was performed and not performed.
  
  
  METHODS
  ART program, Birmingham Women's Hospital, Birmingham, United Kingdom.
  
  
  METHODS
  Patients undergoing IVF or ICSI cycles with transfer on day 2.
  
  
  METHODS
  Culture of all fertilized embryos.
  
  
  METHODS
  Number of fertilized embryos cleaving to the 2-cell stage on day 1, embryo quality, implantation rates, and pregnancy rates.
  
  
  RESULTS
  Patients with early-cleaving 2-cell embryos had significantly higher pregnancy and implantation rates (45 of 100 [45.0%] and 58 of 219 [25.5%], respectively) than did patients without early-cleaving 2-cell embryos (31 of 130 [23.8%] and 43 of 290 [14.8%], respectively). In weeks during which preselection was used, the overall pregnancy and implantation rates of the clinic improved.
  
  
  CONCLUSIONS
  The presence of early-cleaving 2-cell embryos improves a patient's chance of achieving pregnancy. Use of more stringent embryo selection criteria can improve overall pregnancy rates.
authors.affiliation: Assisted Conception Unit, Birmingham Women's Hospital, Edgbaston, Birmingham, United Kingdom. Denny.Sakkas@yale.edu
authors.forename: D
authors.initials: D
authors.lastname: Sakkas
authors.forename: G
authors.initials: G
authors.lastname: Percival
authors.forename: Y
authors.initials: Y
authors.lastname: D'Arcy
authors.forename: K
authors.initials: K
authors.lastname: Sharif
authors.forename: M
authors.initials: M
authors.lastname: Afnan
mesh_terms: D000328:Adult; D004624:Embryo Transfer; D005314:Embryonic and Fetal Development / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D011247:Pregnancy; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods; D013997:Time Factors