title: The pregnancy rates of cohorts of idiopathic infertility couples gives insights into the underlying mechanism of infertility.
abstract: OBJECTIVE
  To determine causes of "idiopathic" infertility, the IVF-ET experience of three cohorts of couples with this diagnosis was examined.
  
  
  METHODS
  Three cohorts of idiopathic infertility couples undergoing IVF-ET: a "failed IUI" group, three previous controlled ovarian hyperstimulation (COH)-IUI cycles with no pregnancies; a "conversion" group, patients converted during a COH-IUI cycle to IVF-ET because of excess follicle numbers; and a "direct IVF" group, patients proceeding directly to IVF-ET were compared.
  
  
  METHODS
  A tertiary referral reproductive medicine unit.
  
  
  METHODS
  Forty-one idiopathic infertility couples.
  
  
  METHODS
  In vitro fertilization-ET.
  
  
  METHODS
  Number of oocytes retrieved, percent oocytes fertilized, number embryos per ET, implantation rate, percent pregnancy per cycle.
  
  
  RESULTS
  The cohorts had similar fertilization rates and mean (+/- SD) number of pre-embryos transferred. The conversion group demonstrated a higher pregnancy rate (PR) per cycle and a higher E2 concentration than the other groups. The PR of 35.0% in the direct IVF group appeared higher than the 16.7% rate observed in the failed IUI group.
  
  
  CONCLUSIONS
  Our observation of a lower PR in couples in the failed IUI group (16.7%) than in couples in the direct IVF group (35.0%) suggests pre-embryo developmental problems or implantation problems as likely important etiologies for a large proportion of idiopathic infertility couples. However, as the conversion group demonstrated both a significantly higher E2 concentration ([E2]) and per cycle PR than the other cohorts with similar fertilization and pre-embryo transfer rates. Subjects converted in a COH-IUI cycle to IVF-ET are thus either more likely to produce pre-embryos more genetically capable of continued development to implantation stage (i.e., better oocytes recruited and fertilized) or due to the higher [E2] to have endometrium more receptive to implantation. Neither undiagnosed tubal factors nor fertilization problems appear to be major etiologic contributors.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Western Ontario, London, Canada.
authors.forename: J S
authors.initials: JS
authors.lastname: Martin
authors.forename: J A
authors.initials: JA
authors.lastname: Nisker
authors.forename: J I
authors.initials: JI
authors.lastname: Parker
authors.forename: B
authors.initials: B
authors.lastname: Kaplan
authors.forename: I S
authors.initials: IS
authors.lastname: Tummon
authors.forename: A A
authors.initials: AA
authors.lastname: Yuzpe
mesh_terms: D000328:Adult; D015331:Cohort Studies; D004624:Embryo Transfer; D004958:Estradiol / Q000097:blood; D005260:Female; D005307:Fertilization in Vitro; D007987:Gonadotropin-Releasing Hormone / Q000819:agonists; D006801:Humans; D007246:Infertility / Q000209:etiology / Q000628:therapy*; D007317:Insemination, Artificial, Homologous; D008297:Male; D008596:Menotropins / Q000627:therapeutic use; D009994:Osmolar Concentration; D011247:Pregnancy; D017211:Treatment Failure
chemical_list: D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D008596:Menotropins