According to researchers, drinking a pint of beer a day doubles a man's odds of becoming a father. But the same study showed that if you want to start a family, it could be a good idea to cut down on coffee as just two cups a day seemed to slash a couple's odds of having a baby.
A second study has also shown that vegetarians have lower sperm counts than other men – with the sperm they made was of poorer quality.
In the first study, researchers from the Massachusetts General Hospital in Boston studied 105 men whose wives and girlfriends were undergoing IVF.
The men, who had an average age of 37, filled in an extensive dietary questionnaire that included questions about alcohol intake and caffeinated drinks.
The amount of alcohol consumed by the would-be fathers was relatively moderate, with the biggest drinkers downing just under three units a day on average. A pint of Stella Artois has 2.7 units.
The tests showed that there was no link between the amount of caffeine or alcohol they took in and the quality of their sperm.
But those who had the most alcohol had a 57 per cent chance that a session of IVF would result in a baby being born. This was twice the 28 per cent success rate of those who drank the least.
