The association between male smoking and live birth rates remains unclear. One explanation for the unexplained infertility is damage to the sperm DNA. However, it remains, to date, an understudied area of investigation.
Additional support for this theory comes from understanding the harmful components that make up cigarettes. Smoking also reduces the levels of antioxidants, which play a vital role in neutralising the effects of harmful free radicals. An excess of free radicals can cause oxidative stress and will compromise normal cellular processes.
Some suggest a link between obesity and reduced semen quality, reduced sperm concentration and reduced motility. Obesity is also thought to cause a lower ejaculate volume and increase a male’s risk of experiencing erectile dysfunction. As with smoking, obesity correlates with a high DFI; those men with a higher BMI are more susceptible to damaged DNA.