The jury’s out on this. It’s not scientifically proven one way or another that a man’s underwear makes any difference to his chances of making a baby. The idea is that wearing loose boxer shorts instead of tight briefs may help fertility by keeping his testicles cool, which helps with sperm production. Marilyn Glenville says: “There’s some evidence that men shouldn’t balance laptops on their laps with their legs closed. It can get very hot which may not necessarily be good for sperm.”