Men should consider freezing their sperm at the age of 18 to reduce the chance of having a disabled child, a British expert has suggested.

The risk of having a child with disorders such as autism and schizophrenia increases the older a father gets, emerging research suggests.

This is thought to be linked to the quality of a man’s sperm, which deteriorates with age.

Dr Kevin Smith, a bioethicist at Abertay University in Dundee, today called for the NHS to offer all young men free sperm banking, so they can store high-quality sperm until they are ready to be fathers.

Dr Smith said a public health campaign is needed, to raise awareness of the problem – and warned that if nothing is done there would be a gradual reduction of ‘human fitness in the long term’.