Effects of cigarette smoking on human semen quality.

The effects of cigarette smoking on sperm quality were evaluated from a group of males undergoing initial screening for infertility. Out of a total of 674 males, 618 (selected based on established criteria) were studied. Detailed smoking history was obtained by direct interview. Tests were conducted on semen characteristics (volume, sperm density, viability, motility, and morphology). Smokers had significantly poorer sperm density (p < .04), a lower percentage of normal sperm morphology (p < .001) and a higher percentage of headpiece spermatozoa defects (p < .01) compared with the nonsmokers. Significant trends were also observed for different categories of cigarette-years with sperm density, percentage of normal spermatozoa morphology, and percentage of spermatozoa with headpiece defect. Cigarette smoking appears to affect sperm density and the morphology of spermatozoa, especially the headpiece. A dose-response relationship of cigarette smoking and spermatogenesis is suggested.