I’m 45 and my partner and I are trying for a baby. Will my sperm be up to the job at this age?
Jack Rose, by email

Everyone knows that women have a biological clock, but few know that men do too. As a man gets older he produces fewer sperm, and they are more sluggish. The most reliable way to find out if yours are up to the job is to try for a baby.

Many older men have fathered children – Charlie Chaplin became a dad at 73. It takes just one healthy sperm, so even men with a low sperm count can father children.

To give yourself the best chance of making healthy sperm, don’t smoke or use recreational drugs or steroids, stick to safe levels of alcohol and stay active. Get plenty of vitamins A, C and E, zinc and selenium from your diet.