For decades women have been told they will put their children at risk if they wait to start a family.
New research is claiming that Men should start a family before they reach the age of 35, in order to avoid health risks to their unborn babies.
The extensive study from the Stanford University School of Medicine, tracked a staggering 40-million babies and discovered some shocking results.
And it was found that the risk of birth complications started to increase when fathers were in their mid-30s, while they significantly rose from the age of 45.
For decades women have been told they will put their children at risk if they pursue a career first and leave it until they are older to have a family.
But the new study, published in the British Medical Journal, shows men should also take responsibility.
Researcher Professor Michael Eisenberg, of Stanford University School of Medicine, said: 'We tend to look at maternal factors in evaluating associated birth risks.
'But this study shows that having a healthy baby is a team sport, and the father's age contributes to the baby's health, too.'
He said once a man ages further into their 40s and 50s, he accumulates on two new mutations in the DNA of his sperm, which could impact the health of an unborn child.
