title: Limited implantation success of direct-cleaved human zygotes: a time-lapse study.
abstract: OBJECTIVE
  To evaluate embryos with direct cleavage (≤5 hours) from two to three cells (DC2-3) and correlate this morphokinetic parameter to implantation and ongoing pregnancy.
  
  
  METHODS
  Clinical multicenter retrospective study.
  
  
  METHODS
  Private in vitro fertilization (IVF) centers.
  
  
  METHODS
  From three clinics, a total of 979 treatments including 5,225 embryos using autologous or donated oocytes, of which 1,659 embryos were transferred.
  
  
  METHODS
  None.
  
  
  METHODS
  Clinical pregnancy confirmed by ultrasound in week 7.
  
  
  RESULTS
  Of the total embryo cohort, 715 (13.7%) underwent direct cleavage from two to three cells, 1,659 embryos were transferred to recipients, and 109 of the transferred embryos cleaved directly from two to three cells (6.6%). Only one DC2-3 embryo was known to result in a clinical pregnancy (1%) and 80 (73.4%) DC2-3 embryos did not implant. Of the 1,550 embryos transferred not showing DC2-3, 203 embryos were from treatments with 100% implantation (13.1%), and 804 (51.8%) embryos did not implant. The known implantation rate of DC2-3 embryos was statistically significantly lower than for embryos with a normal cleavage pattern (1.2% vs. 20.2%, respectively).
  
  
  CONCLUSIONS
  Embryos with DC2-3 had a statistically significantly lower implantation rate than embryos with a normal cleavage pattern, suggesting that rejection of these embryos for transfer could improve the implantation rate.
authors.affiliation: Instituto Valenciano de Infertilidad Valencia, Universidad de Valencia, Valencia, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Rubio
authors.forename: Reidun
authors.initials: R
authors.lastname: Kuhlmann
authors.forename: Inge
authors.initials: I
authors.lastname: Agerholm
authors.forename: John
authors.initials: J
authors.lastname: Kirk
authors.forename: Javier
authors.initials: J
authors.lastname: Herrero
authors.forename: María-José
authors.initials: MJ
authors.lastname: Escribá
authors.forename: José
authors.initials: J
authors.lastname: Bellver
authors.forename: Marcos
authors.initials: M
authors.lastname: Meseguer
mesh_terms: D000328:Adult; D003718:Denmark / Q000453:epidemiology; D010064:Embryo Implantation; D004624:Embryo Transfer / Q000379:methods* / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D013030:Spain / Q000453:epidemiology; D016896:Treatment Outcome; D055815:Young Adult; D015053:Zygote / Q000637:transplantation*