title: Cigarette smoking and semen quality.
abstract: OBJECTIVE
  To determine whether cotinine levels provide stronger evidence for an association between smoking and semen quality than the number of cigarettes smoked per day or years smoked controlling for potential confounders and effect modifiers.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Male volunteers at the Reproductive Endocrinology-Fertility Laboratory.
  
  
  METHODS
  Eighty-eight men (ages 18 to 35 years) provided a semen, urine, and blood specimen and completed a self-administered questionnaire concerning smoking and demographic information as well as caffeine and alcohol consumption. Urine, blood, and semen cotinine levels were analyzed via RIA.
  
  
  METHODS
  Standard clinical semen analysis.
  
  
  RESULTS
  Number of cigarettes smoked per day, years smoked, and log-transformed cotinine levels were associated negatively with semen quality (density, total count, and motility). The association was evident among men age > or = 22 years. For example, the correlation coefficient for the overall association between logged urine cotinine and logged sperm density was -0.23; those stratified by age were 0. 13 (age < 22 years) and - 0. 39 (age > or = 22 years). Potential confounders included in regression models did not diminish the associations.
  
  
  CONCLUSIONS
  Smoking is associated with lowered semen quality.
authors.affiliation: The University of North Carolina, Chapel Hill, 27599-7400, USA.
authors.forename: M F
authors.initials: MF
authors.lastname: Vine
authors.forename: C K
authors.initials: CK
authors.lastname: Tse
authors.forename: P
authors.initials: P
authors.lastname: Hu
authors.forename: K Y
authors.initials: KY
authors.lastname: Truong
mesh_terms: D000293:Adolescent; D000328:Adult; D003367:Cotinine / Q000378:metabolism; D003430:Cross-Sectional Studies; D006801:Humans; D008297:Male; D012661:Semen / Q000166:cytology*; D012907:Smoking / Q000009:adverse effects* / Q000473:pathology / Q000503:physiopathology; D013076:Sperm Count; D013081:Sperm Motility
chemical_list: D003367:Cotinine