title: Semen quality according to prenatal coffee and present caffeine exposure: two decades of follow-up of a pregnancy cohort.
abstract: BACKGROUND
  A few studies have investigated the association between male caffeine consumption in adult life and semen quality with conflicting results, but so far no studies have explored the effect of prenatal coffee exposure. We studied the association between prenatal coffee and current caffeine exposure and semen quality and levels of reproductive hormones.
  
  
  METHODS
  From a Danish pregnancy cohort established in 1984-1987, 347 sons out of 5109 were selected for a follow-up study conducted 2005-2006. Semen and blood samples were analyzed for conventional semen characteristics and reproductive hormones and were related to information on maternal coffee consumption during pregnancy and present caffeine consumption. Data were available for 343 men.
  
  
  RESULTS
  There was a tendency toward decreasing crude median semen volume (P = 0.06) and adjusted mean testosterone (P = 0.06) and inhibin B (P = 0.09) concentrations with increasing maternal coffee consumption during pregnancy. Sons of mothers drinking 4-7 cups/day had lower testosterone levels than sons of mothers drinking 0-3 cups/day (P = 0.04). Current male caffeine intake was associated with increasing testosterone levels (P = 0.007). Men with a high caffeine intake had approximately 14% higher concentration of testosterone than those with a low caffeine intake (P = 0.008).
  
  
  CONCLUSIONS
  The results observed in this study are only tentative, but they do not exclude a small to moderate effect of prenatal coffee exposure on semen volume and levels of reproductive hormones. Present adult caffeine intake did not show any clear associations with semen quality, but high caffeine intake was associated with a higher testosterone concentration.
authors.affiliation: Department of Occupational Medicine, Aarhus University Hospital, Aarhus C, Denmark. craha@as.aaa.dk
authors.forename: C H
authors.initials: CH
authors.lastname: Ramlau-Hansen
authors.forename: A M
authors.initials: AM
authors.lastname: Thulstrup
authors.forename: J P
authors.initials: JP
authors.lastname: Bonde
authors.forename: J
authors.initials: J
authors.lastname: Olsen
authors.forename: B H
authors.initials: BH
authors.lastname: Bech