The impact of cigarette smoking on human semen parameters and hormones

In this prospective study, semen parameters and hormone concentrations of infertile smokers were compared with infertile non- and ex-smokers. We also determined how many men with idiopathic infertility would stop smoking in an attempt to improve their fertility.

1104 men (517 non-smokers, 109 ex-smokers and 478 smokers) with infertility for at least 1 year were evaluated. Evaluation included medical history, physical examination, hormone analysis and two semen analyses. Prior to the second semen analysis, smokers were urged to quit smoking.

Smokers were significantly younger (P < 0.001), had significantly more round cells in their ejaculates (P = 0.003), and the percentage of ejaculates with > 1 x 10(6)/ml leukocytes was higher in smokers (P < 0.001). Increased free and total serum testosterone (P < 0.001) and decreased prolactin levels (P < 0.001) were found in smokers. No differences were found between non-smokers and ex-smokers. Only 23.1% of the smokers versus 46% non-smokers (P < 0.001) returned for a second semen analysis, 14 of whom reduced and 15 of whom quit smoking completely. Testosterone levels were significantly lower in those who were able to stop or reduce smoking (P < 0.001).

Smoking does not affect conventional semen parameters, but significantly increases round cells and leukocytes. Only a few idiopathic infertile smokers were able to quit smoking.