title: Reduced fertility among overweight and obese men.
abstract: BACKGROUND
  Overweight and obese men have been reported to have lower sperm counts and hormonal changes, but data are lacking regarding effects on couple fertility.
  
  
  METHODS
  We examined the relationship between male body mass index (BMI) and infertility in couples enrolled in the Agricultural Health Study in the United States. The analysis sample was limited to couples (wife <40 years old) with an attempt at pregnancy in the last 4 years based on pregnancy and fertility data provided by wives. Infertility was defined as not conceiving a pregnancy after at least 12 months of unprotected intercourse regardless of whether or not a pregnancy ultimately occurred. Self-reported weight and height were used to calculate BMI (kg/m). Adjusted odds ratios (aORs) for infertility associated with increases in male BMI were calculated with logistic regression.
  
  
  RESULTS
  Adjusting for potential confounders, a 3-unit increase in male BMI was associated with infertility (aOR = 1.12; 95% confidence interval = 1.01-1.25; n = 1329). There was a dose-response relationship, and the BMI effect was stronger when the data were limited to couples with the highest-quality infertility data. The association between BMI and infertility was similar for older and younger men, suggesting that erectile dysfunction in older men does not explain the association.
  
  
  CONCLUSIONS
  This report of lower fertility in overweight and obese men needs replication. If the findings are robust, programs to prevent obesity may improve men's reproductive health and save medical costs for infertility treatment.
authors.affiliation: Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA. Markku.Sallmen@ttl.fi
authors.forename: Markku
authors.initials: M
authors.lastname: Sallmén
authors.forename: Dale P
authors.initials: DP
authors.lastname: Sandler
authors.forename: Jane A
authors.initials: JA
authors.lastname: Hoppin
authors.forename: Aaron
authors.initials: A
authors.lastname: Blair
authors.forename: Donna Day
authors.initials: DD
authors.lastname: Baird
mesh_terms: D000328:Adult; D000383:Agriculture / Q000706:statistics & numerical data; D015992:Body Mass Index; D016021:Epidemiologic Studies; D006801:Humans; D007248:Infertility, Male / Q000453:epidemiology* / Q000209:etiology; D007484:Iowa / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D009765:Obesity / Q000453:epidemiology*; D016017:Odds Ratio; D014481:United States / Q000453:epidemiology