London: Researchers have now found proof that men have less sex after they become a father for the first time.
A study of more than 400 young men in the Philippines found that their sex lives went down after they had their first child.
The latest research shows that the greater the fall in testosterone, the less sex men reported.
Lee Gettler, an anthropologist at the University of Notre Dame in Indiana, gathered medical and lifestyle information on the men from the ages of 21 to 26 years old and found there were physiological and behavioural changes as some of them married and had children.
When men got married their testosterone levels fell, and declined even further when they had their first child. That led to the question of whether falling testosterone might impact on their sex lives.