Older fathers include Simon Cowell, whose son Eric was born in 2014 when he was 54
It is not only women who face the ticking of their biological clock.
Men who try to have a child in their fifties are a third less likely to conceive than younger men, a study suggests.
Experts now believe when women hit the menopause, at the average age of 51, men see a similar decline in their sperm quality.
Researchers tracked more than 4,200 men trying to have a baby through IVF.
They found men aged 51 and older were 34 per cent less likely to conceive than those under 35.
Although there are many ageing celebrity fathers, from Rod Stewart to Mick Jagger, the evidence suggests sperm DNA becomes damaged with age.
This may explain the higher risk of older men having children with autism and schizophrenia, and suggests women may be better off choosing a man under 50 if they want a child.
Dr Guy Morris, the research fellow who led the study from University College London, said: 'Men's sperm seems to be unaffected by their age right up to the age of 50, which is when there is a significant decline.
'In women, they lose the function of their reproductive organs when they go through the menopause.
'In men, the quality and quantity of sperm production declines with age and this seems to have a significant effect after the age of 50.'
Older fathers in showbusiness include Simon Cowell, whose son Eric was born in 2014 when he was 54, Frank Skinner, whose son Buzz Cody was born in 2012 when he was 55 and Rod Stewart, who was 66 when his eighth child, Aiden, was born in 2011.
These cases are feared to further the 'myth' that men can put off having a child until middle age.
Researchers analysed the records of 4,271 men having IVF at the Centre for Reproductive and Genetic Health (CRGH) in London between 2009 and last year.
They found the pregnancy rate fell as men got older, with almost half of under-35s achieving success but only 35.2 per cent of men aged 41 to 45.
Sir Mick Jagger, famous for his time in The Rolling Stones, gave birth to his eighth child at the age of 73 in 2016
Men who try to have a child in their fifties are a third less likely to conceive than younger men, a study of men having a baby with IVF suggests. Stock photo
The pregnancy rate in partners of men aged 46 to 50 fell to 32.8 per cent and hit just 30.5 per cent for men aged 51.
When women's ages were taken into account, the slump in pregnancy chances was most significant for men aged 51.
Men of this age and older were 34 per cent less likely to be successful in IVF than under-35s, showing the fertility of men this age falls significantly.
Dr Morris, who also works at CRGH, said: 'There may well be a public perception that male fertility is independent of age.
'Stories of celebrity men fathering children into their sixties may give a skewed perspective on the potential risks of delaying fatherhood.'
Dr Morris, who presented the findings at the annual meeting of the European Society of Human Reproduction and Embryology in Vienna, added: 'In the context of this emerging evidence for the deleterious effect of increasing paternal age, our data certainly support the importance of educating men about their fertility and the risks of delaying fatherhood.'
A previous study, from Beth Israel Deaconess Medical Centre in Boston, found men aged 40 to 42 were a