'Pass on the bacon for better sperm'

For men trying to conceive a baby, hold off on the bacon and processed meats, a new US study suggests.

Harvard University researchers say that the intake of bacon and processed meat is associated with lower semen quality in men. Researchers presented their findings at this week's American Society for Reproductive Medicine conference in Boston.

To reach their findings, the scientists analyzed sperm samples from 156 volunteers against each subjects' food diaries. After adjusting for factors such as age and BMI, the team found a negative association between processed meats, including hot dogs and bacon, and sperm quality. Even eating more than a half portion a day had a significant impact on lower levels of "normal"-shaped sperm, the researchers said. However, the study didn't account for sperm count or motility, which can also affect fertility.

While caffeine and alcohol have no apparent effect on fertility, eating white-meat fish, such as cod and halibut, showed a positive association with sperm health, the findings suggest.

Previous studies have suggested that wearing tight underwear could slow sperm production by raising the temperature of the testicles.