If you fancy a pint after work then this might be the perfect excuse. Because 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 just two cups of coffee a day seemed to slash a couple's odds of having a baby.
Researchers from the Massachusetts General Hospital in Boston studied 105 men whose partners 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.
When the researchers looked at caffeine intake, they found that birth rates plummeted from 52 per cent among those who had very little caffeine to just 19 per cent for those who had the most. The damage was done above 265mg of caffeine a day. A mug of filter coffee contains 140mg.
The American Society for Reproductive Medicine's annual conference in Honolulu heard that the results could not be explained away by factors such as the men's age or weight.
Researchers were unsure why caffeine and alcohol had such a noticeable effect on birth rates when it seemed to have no impact on the quality of the sperm.
However, Dr Allan Pacey, from Sheffield University, said: "Moderate social drinking can be of benefit for couples trying to conceive either naturally or during assisted conception because it helps to reduce stress."
- Daily Mail