CIGARETTE-SMOKING AND SEMEN QUALITY

Objective: To determine whether cotinine levels provide stronger evide nce for an association between smoking and semen quality than the numb er of cigarettes smoked per day or years smoked controlling for potent ial confounders and effect modifiers. Design: Cross-sectional study. S etting: Male volunteers at the Reproductive Endocrinology-Fertility La boratory. Participants: Eighty-eight men (ages 18 to 35 years) provide d 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. Main Outcome Measure: Standard clinical semen analysis. Results: Number of cigarettes smoked per day, years sm oked, and log-transformed cotinine levels were associated negatively w ith semen quality (density, total count, and motility). The associatio n was evident among men age greater than or equal to 22 years. For exa mple, the correlation coefficient for the overall association between logged urine cotinine and logged sperm density was -0.23; those strati fied by age were 0.13 (age <22 years) and -0.39 (age greater than or e qual to 22 years). Potential confounders included in regression models did not diminish the associations. Conclusions: Smoking is associated with lowered semen quality.