The effect of cigarette smoking on the semen parameters of infertile men.

36.9% of men worldwide use tobacco. Previous studies suggest a negative effect of cigarette smoking on semen quality, but the results are contradictory. We have studied the effects of smoking on the semen characteristics such as sperm concentration, semen volume, sperm motility, sperm vitality and sperm morphology in a large group of infertile men. This retrospective study was conducted on a total of 5146 infertile men with at least one year of idiopathic infertility, who admitted to the Centre for Reproductive medicine (CRG) at the Brussels University Hospital, Belgium between 2010 and 2017. The smokers were classified as mild (1-10 cigarettes/d), moderate (11-20 cigarettes/d) or heavy smokers (> 20 cigarettes/d). Semen analysis was performed for all patients. Statistical analysis was performed using the R software package and t-test or Mann-Whitney U tests were used, group comparisons were performed using ANOVA, ANCOVA or Kruskal-Wallis tests as appropriate. A p-value <0.05 was considered as statistically significant. Comparing the semen parameters in the two global groups showed that smoking had a significant decrease in semen volume ( We concluded that smoking had a significant and independent effect on the sperm concentration in a semen analysis. Other parameters, like semen volume, sperm motility, sperm vitality and sperm morphology were not influenced by smoking.