Smoking and Male Fertility: Cigarette smoking (including second-hand by being near a smoker) may negatively affect a man’s semen. This is important especially if a man is trying to have children. Some studies have shown decreased sperm count (average approximately 20% decreased and based on how much one is exposed to), motility (movement), abnormal sperm shape and sperm maturation have been described (more). Smokeless tobacco is not any better and also has the same negative effect on semen parameters (more). Further cigarette smoking has been shown to change sperm DNA packaging and changes in gene expression which may certainly affect fertility (more).
Just as DNA damage can occur in women’s eggs from smoking, it has been identified that sperm DNA may be bound directly by tobacco smoke components. Sperm additionally have increased chance of getting an extra Y chromosome (DNA) with increased concentrations of smoking byproducts in the urine (more). DNA damage is transmitted from parents who smoke (fathers may play a more significant role than mothers) to offspring and can lead to miscarriages and birth defects. Even for those couples that seek in vitro fertilization (where sperm and egg are united outside the body and then replaced in the female’s uterus), smokers require twice as many attempts to conceive as nonsmokers.
Smoking and Erection: Severity of erectile dysfunction (ED) significantly correlates with the level of exposure to smoking regardless of increased cardiovascular risk (more). ED has been reported in 3.7% of current smokers, 2.0% of former smokers, and 2.2% of men who never smoked. Quitting smoking could prevent ED worsening in 25% of cases. Cigarette smoking causes arterial tightening (constriction), with reduction in oxygen supply and increased damage to healthy tissues (called endothelial tissues). Within 24-36 hours of stopping smoking, the bloodflow characteristics were improved in one study (more).
Bottom Line: While the overall effect of smoking remains difficult to assess on men’s fertility (due to factors including partner issues and other unhealthy habits of smokers that cannot be sorted out with available studies), data exists to discourage smoking in couples that desire children. Stop smoking and improve not just your breathing and fertility, but also possibly your sex life.
For tips on quitting smoking, see the CDC (Centers for Disease Control, US Government) website. Due to popular request, we will soon be posting info on the cancer risks of smoking (including bladder and kidney cancer).
–Matthew Wosnitzer, M.D.
September 24, 2014