Simon and New York socialite Lauren have revealed they're expecting a baby boy but have not publicly revealed the due date, although it could be soon as Lauren was recently thrown a baby shower by friends.
During a recent press conference for US X Factor, Simon admitted he hadn't been invited to the baby shower but had seen how generous the guests had been.
"I wasn't there. I wasn't invited, literally," he said (via People). "There were a lot of (gifts). There were a lot of clothes. It looks like I'm having 100 kids right now, there are so many."
According to E! Online, those who were invited included Simon's ex-girlfriends Terri Seymour and Mezhgan Hussainey, while Simon opted to spend the afternoon at a local hotel.
The music mogul was spotted with his heavily pregnant lover leaving Sur restaurant in Los Angeles on Sunday night (15 December), a few hours after Sam Bailey was named the latest winner of his X Factor franchise.
Simon had earlier congratulated Sam on her win via Twitter, adding that he liked her version of Demi Lovato's 'Skyscraper', which she has released as her winner's song. Interestingly, Simon is currently a judge on the US version of X Factor alongside Demi.
He later tweeted: "Thank you to the entire production team who worked on X factor uk. And of course the judges and the talent. And to everyone who watched. And next week it's the X factor USA final. You have no idea what goes on behind the scenes! It's going to be a great final. Watch and see. (sic)."
There have been plenty of rumours floating around that Simon will return to the UK show as a judge next year.
While he hasn't commented on the speculation, there will certainly be room for him as Gary Barlow and Sharon Osbourne have both confirmed they won't be returning for the eleventh series.
Louis Walsh had also announced his exit but appears to have backtracked in recent weeks, while Nicole Scherzinger has yet to reveal her plans for next year.
But before any decisions are made on the X Factor UK judging panel, Simon has something far more important creeping up on the horizon: the birth of his first child.
More celebrities expecting babies in Reveal's gallery below:
Copyright: Vimeo / Weiss Eubanks