Cigarette smoking and the risk of male factor subfertility: minor association between cotinine in seminal plasma and semen morphology.

OBJECTIVE: To evaluate the impact of cigarette smoking on male factor subfertility and the semen parameters of sperm count, motility, and morphology by questionnaire and determination of the cotinine concentrations in blood and seminal plasma of fertile and subfertile males.
DESIGN: Case-control study of 107 fertile and 103 subfertile males who provided a standardized blood and semen specimen and completed a self-administered questionnaire about their smoking habits.
SETTING: Outpatient fertility clinic of the University Medical Centre St. Radboud, Nijmegen, The Netherlands. PATIENT(S): One hundred seven fertile and 103 subfertile males. INTERVENTION(S): Vena puncture and semen collection. MAIN OUTCOME MEASURE(S): Blood and seminal plasma cotinine levels in relation to semen parameters. RESULT(S): A higher frequency of cigarette smoking was observed in subfertile males than in fertile males, with an odds ratio of 1.7 (95% confidence interval, 0.9-3.2). The self-reported number of cigarettes smoked per day correlated with the cotinine concentrations in blood and seminal plasma for both groups. A small but statistically significant correlation was found between cotinine concentrations in seminal plasma and the percentage of abnormal sperm morphology, but not for other semen parameters (r(s) = 0.19). CONCLUSION(S): Although the mechanism of the toxicity of cotinine on sperm morphology is not clear, this study indicates only a minor effect of cigarette smoking on male factor subfertility, which is probably due to compounds in cigarette smoke other than nicotine (cotinine).