title: Is the zona pellucida thickness of human embryos influenced by women's age and hormonal levels?
abstract: OBJECTIVE
  To evaluate whether zona pellucida thickness (ZPT) of human embryos is correlated with maternal age, patient's hormonal status, embryo quality, and IVF outcomes.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  University-affiliated IVF clinic.
  
  
  METHODS
  Couples undergoing IVF-ET cycles.
  
  
  METHODS
  Zona measurements, clinical data collection.
  
  
  METHODS
  Correlation between the ZPT and maternal age, basal FSH and E(2) levels, stimulation protocols, cause of infertility, embryo quality, and implantation/pregnancy rates.
  
  
  RESULTS
  The measurements of ZPT were collected from 5,184 day 3 human embryos originated from 744 IVF patients. The overall mean ZPT was 16.18 ± 2.00 μm. No significant correlation was observed between the ZPT and the patient's age, E(2) values on the day of hCG administration, basal concentration of serum FSH, stimulation protocol, infertility diagnosis, and implantation/pregnancy rates. The ZPT was strongly influenced only by the embryo quality: Embryos with good morphology exhibited considerably thinner ZP compared with those of less favorable morphology (mean 15.87 ± 2.48 μm vs. 16.36 ± 2.57 μm, respectively). The ZPT had no significant impact on the implantation and pregnancy rates.
  
  
  CONCLUSIONS
  The thickness of the human ZP of day 3 embryos is not influenced by women's age and hormonal levels. The strong correlation between ZPT and embryo quality suggests that thickness of ZP depends on inherent embryo properties. The overall ZPT is not a good predictive indicator for IVF clinical outcomes.
authors.affiliation: Create Fertility Centre, Toronto, Ontario, Canada. hanna@createivf.com
authors.forename: Hanna
authors.initials: H
authors.lastname: Balakier
authors.forename: Agata
authors.initials: A
authors.lastname: Sojecki
authors.forename: Gelareh
authors.initials: G
authors.lastname: Motamedi
authors.forename: Siamak
authors.initials: S
authors.lastname: Bashar
authors.forename: Rodica
authors.initials: R
authors.lastname: Mandel
authors.forename: Clifford
authors.initials: C
authors.lastname: Librach
mesh_terms: D000328:Adult; D048429:Cell Size; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000166:cytology* / Q000648:ultrastructure*; D005260:Female; D005307:Fertilization in Vitro; D006728:Hormones / Q000032:analysis / Q000097:blood*; D006801:Humans; D007246:Infertility / Q000097:blood / Q000175:diagnosis / Q000628:therapy; D008297:Male; D008423:Maternal Age; D009994:Osmolar Concentration; D011247:Pregnancy; D011379:Prognosis; D020554:Sperm Injections, Intracytoplasmic; D055815:Young Adult; D015044:Zona Pellucida / Q000502:physiology*
chemical_list: D006728:Hormones