Health expert Dr Michael Mosley says there are three things men need to change if they're trying to have a baby - and finding it difficult to conceive. Dr Mosley, writing for MailOnline, explained that a recent major study found a drop in sperm counts.
The research in Human Reproduction Update found men in the Americas, Asia, Africa and Europe had all seen at least a 50 per cent decline in sperm counts. Lower sperm counts make it harder for couples to conceive.
One study predicts that the world's population will start to fall sharply as the number of babies being born drops.
Dr Mosley says one of the factors possible causing a drop in sperm counts is PFAs - a chemical found in drinking water, food packaging and furniture coatings.
He said: "Filtering your tap water may help, while eating less junk food is also a good idea, as the packaging it comes in often contains PFAs."
He added: "Non-stick pans are also a source of PFAs, so discard them if they get badly scratched and don't use them to fry at high heat."
Dr Mosley concluded: "If your count is low and you are hoping to have children, then it may be worth losing weight and switching to boxer shorts — as studies have shown that the testes can overheat when wearing tight underwear and this can contribute to a low sperm count."