title: Regional differences in waiting time to pregnancy among fertile couples from four European cities.
abstract: BACKGROUND
  A previous European study found a longer time to pregnancy (TTP) among fertile women from Paris compared with women from other Western European countries. A co-ordinated, cross-sectional study of pregnant couples from Denmark (Copenhagen), France (Paris), Scotland (Edinburgh) and Finland (Turku) was therefore undertaken to assess differences in waiting TTP among couples from these cities.
  
  
  METHODS
  Pregnant women were invited to participate when they showed up for their first antenatal visit in one of the four centres. Inclusion criteria included that their partner was 20-45 years of age and born in the country in which he was currently living and that the pregnancy was achieved without fertility treatment. Both partners filled in a questionnaire and the man underwent a physical examination and delivered a semen sample (Turku: n = 237, Copenhagen: n = 302, Edinburgh: n = 212, Paris: n = 191).
  
  
  RESULTS
  French couples had a decreased probability of conception compared with couples from the other three countries, although only after adjustment for confounders. No significant differences between couples from the three other countries were found.
  
  
  CONCLUSIONS
  The observed geographical differences in TTP remain unexplained and were not due to differences in semen quality, but may be caused by varying exposures to environmental factors or psychological distress. In addition, selection bias due to the low participation rates cannot be ruled out. Future studies examining the causes for geographical differences in TTP are needed.
authors.affiliation: Department of Growth and Reproduction, section GR-5064, Rigshospitalet, The Juliane Marie Centre, Blegdamsvej 9, DK-2100 Copenhagen, Denmark. tkjensen@health.sdu.uk
authors.forename: T K
authors.initials: TK
authors.lastname: Jensen
authors.forename: R
authors.initials: R
authors.lastname: Slama
authors.forename: B
authors.initials: B
authors.lastname: Ducot
authors.forename: J
authors.initials: J
authors.lastname: Suominen
authors.forename: E H
authors.initials: EH
authors.lastname: Cawood
authors.forename: A G
authors.initials: AG
authors.lastname: Andersen
authors.forename: F
authors.initials: F
authors.lastname: Eustache
authors.forename: S
authors.initials: S
authors.lastname: Irvine
authors.forename: S
authors.initials: S
authors.lastname: Auger
authors.forename: P
authors.initials: P
authors.lastname: Jouannet
authors.forename: M
authors.initials: M
authors.lastname: Vierula
authors.forename: N
authors.initials: N
authors.lastname: Jørgensen
authors.forename: J
authors.initials: J
authors.lastname: Toppari
authors.forename: N E
authors.initials: NE
authors.lastname: Skakkebaek
authors.forename: N
authors.initials: N
authors.lastname: Keiding
authors.forename: A
authors.initials: A
authors.lastname: Spira
mesh_terms: D000328:Adult; D000367:Age Factors; D003430:Cross-Sectional Studies; D003718:Denmark / Q000453:epidemiology; D004522:Educational Status; D004777:Environment; D005260:Female; D005298:Fertility; D005387:Finland / Q000453:epidemiology; D005602:France / Q000453:epidemiology; D006801:Humans; D007246:Infertility / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D010298:Parity; D011247:Pregnancy; D012606:Scotland / Q000453:epidemiology; D012661:Semen / Q000502:physiology; D013076:Sperm Count; D013315:Stress, Psychological; D011795:Surveys and Questionnaires; D013997:Time Factors