Smoking affects male reproduction in the following ways:
Sperm production, sperm morphology, sperm motility and androgen secretion appear to be altered in men who smoke. Studies have shown a decreased sperm density and an increased abnormal sperm morphology among smokers.(1)
Cigarette smoking has been associated with impaired male sexual performance. Possible causes suggested include a deterioration of the blood vessels in the penis,(126) lower mean penile blood pressure among smokers,(127) and impaired hormonal activity.(2)
Nicotine, which causes vasoconstriction (narrowing of the blood vessels),(128) has been identified as a component of tobacco smoke likely to affect potency. However further research is required to confirm these findings.(2)