Smoking can cause DNA damage in sperm which is linked to a child’s risk of cancer, a new study has shown.

The sperm of male smokers contains more damaged DNA, fewer active energy-generating mitochondria and more proteins indicating a revved-up immune response, when compared to non-smokers'. 

"Sperm from these men are thus less capable of achieving fertilization, and, due to high rates of DNA fragmentation, are more likely to lead to early embryo loss and even to consequences in the offspring," said Dr Ricardo Pimenta Bertolla, senior author of the new study from Sao Paulo Federal University in Brazil.

I would recommend men to stop smoking when they wish to achieve fatherhood

Even though the effects of smoking have been known by previous studies, the new study confirms the effects with new patients and helps to demonstrate how the alterations happen, Bertolla said.

Smoking cigarettes may change protein manufacture in the sperm, increasing some and decreasing others, which indicates inflammation in the testicles and other glands, according to the study authors. One of the mechanisms through which smoking alters sperm is by causing excessive seminal inflammation.

"Fertilization is an orchestrated event, in that sperm undergo alterations at specific points in order to be able to fertilize the oocyte," Bertolla said. "If they trigger these effects too soon, they may lose that capacity."

For women, smoking has been linked to earlier menopause, higher risk of miscarriage and ectopic pregnancy in-vitro fertilization, Bertolla said.

"Based on our results, I would recommend men to stop smoking when they wish to achieve fatherhood," Bertolla said. "The whole process of producing a mature sperm takes around three months, so if a man wishes to quit smoking before attempting fatherhood, I would recommend quitting three months ahead of time."