title: Limited importance of pre-embryo pronuclear morphology (zygote score) in assisted reproduction outcome in the absence of embryo cryopreservation.
abstract: OBJECTIVE
  To investigate the hypothesis that Z-score criteria represent a reliable predictor of implantation rate and pregnancy outcome in in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) cycles, excluding the possibility of embryo selection before the embryo transfer.
  
  
  METHODS
  Retrospective clinical study.
  
  
  METHODS
  Centre of Reproductive Medicine, Department of Obstetrics and Gynecology, Arcispedale S. Maria Nuova (ASMN), Reggio Emilia, Italy.
  
  
  METHODS
  We analyzed 393 pregnancies obtained by IVF or ICSI cycles.
  
  
  METHODS
  Morphologic evaluations of Z-score in pre-embryos obtained from IVF or ICSI cycles.
  
  
  METHODS
  Evaluations of Z-scores, implantation rate, and clinical pregnancy outcome.
  
  
  RESULTS
  We did not find any statistically significant correlation between the Z-score of 1032 embryos transferred in 393 embryo transfers and the implantation rate or the pregnancy outcome. In particular, the best Z-score identified (Z1, 7.2%) did not seem to correlate with embryo implantation rate or pregnancy outcomes any better than those with worse scores (Z2, 6.9% and Z3, 85.9%).
  
  
  CONCLUSIONS
  Our results seem to confirm that Z-score alone cannot be considered a better tool than standard morphologic criteria for identifying, controlling, or selecting embryos with a better chance of successful ongoing pregnancy.
authors.affiliation: Centre of Reproductive Medicine, Department of Obstetrics and Gynecology, Arcispedale S. Maria Nuova (ASMN), Reggio Emilia, Italy. alessia.nicoli@asmn.re.it
authors.forename: Alessia
authors.initials: A
authors.lastname: Nicoli
authors.forename: Barbara
authors.initials: B
authors.lastname: Valli
authors.forename: Roberta
authors.initials: R
authors.lastname: Di Girolamo
authors.forename: Barbara
authors.initials: B
authors.lastname: Di Tommaso
authors.forename: Andrea
authors.initials: A
authors.lastname: Gallinelli
authors.forename: Giovanni B
authors.initials: GB
authors.lastname: La Sala
mesh_terms: D000328:Adult; D015925:Cryopreservation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D027724:Reproductive Techniques, Assisted; D012189:Retrospective Studies; D015053:Zygote / Q000502:physiology* / Q000637:transplantation; D017388:Zygote Intrafallopian Transfer / Q000379:methods*