The media mogul is said to be expecting a baby with US socialite Lauren Silverman, according to gossip magazine US Weekly.
The magazine claims multiple sources have exclusively revealed to them that the 53-year-old has fathered a child with her - who is married to his close friend Andrew Silverman.
An insider told the magazine: "She's around 10 weeks along."
Socialite Lauren is estranged from the X Factor judge's good pal Andrew, a real estate mogul in New York but technically still married to him.
Mr Cowell had previously sworn he'd never want kids. He once said: "God, no. I couldn't have children. If I had them here drawing on the walls I'd go nuts.
"With kids, you've got a routine you can't escape from. You've got to be up at a certain time. Got to listen. When all you want to do is sit in a corner thinking."
Last year, though, he hinted in an interview with AOL Music that he hadn't entirely ruled out the idea of someday becoming a father.
Asked if he'd changed his mind about children he told them: "Well...yes. And no. I do really, really like kids, because I can talk to them and listen to them. The problem has always been how much time you need to devote to bringing up kids. I've always dedicated all my life to work, and at 52, I've probably missed the opportunity."
A spokesperson for Simon Cowell from Max Clifford's company told omg! this afternoon: "Max has spoken with Simon today.
"This is a very sensitive issue and all media enquiries are being dealt with by his US attorney Martin Singer."
We are still awaiting comment from Simon Cowell's lawyer.
Simon Cowell is reportedly about to become a DAD if reports in the American press are anything to go by.
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