Amanda, who sits on the Britain's Got Talent judging panel alongside Simon, also believes his unexpected parenthood with Lauren Silverman has come at the right time in his life.
Appearing on The Alan Titchmarsh Show today (17 September), Amanda was asked if Simon's baby news came as a surprise to her.
"Just a little bit, but I'm completely delighted," she replied.
Amanda added: "I don't think his life could've carried on going the way it was going. The universe throws you some curve balls and it's thrown him a brilliant one.
"He will love that baby - he will be overwhelmed by how much. They change your life for the better."
Alan then asked Amanda if she has been asked to be a Godmother by Simon yet.
She replied: "David Walliams will be a fairy Godmother and I will be just a Godmother."
Last month Simon confirmed that he was expecting a baby with US socialite Lauren after the rumour mill went into overdrive.
The music mogul has since attended a scan with Lauren and admitted that he is feeling "very paternal".
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