A new study on smoking effects on fertility was funded by cigarette giant Philip Morris' and it has shown that the sperm of smokers is more likely to fail fertility tests performed in the lab.

Human sperm, like other cells in the body, carry a receptor for nicotine, which means they recognize and respond to nicotine. In this new study, researchers examined whether sperm from chronic tobacco smokers are less likely to binding to the zona, the cover that surrounds an egg. Scientists report that the results could mean that heavy smoking overloads the nicotine receptor in human sperm and in the testes, which leads to a decline in fertilizing potential.

Sperm from almost two-thirds of chronic smokers in the study failed a special test to measure the ability of sperm to fertilize an egg. It was found that, on average, these men had a 75% reduction in fertilizing ability compared to non-smokers.