The little boy is a brother for two-year-old Clemency, her daughter by husband Mike Heron.
Clemency's little baby brother - Wilbur Silverton-Heron - was born 26 June 2014 at 02.53 and weighed 8lbs 3oz.
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Kate Silverton's 'miracle' baby boy Wilbur
Kate called the delivery "a somewhat epic labour."
HELLO! has been told "he was 'back to back' and born facing the sky - causing mummy a few tricky moments - but another lovely natural birth. We are all doing very well indeed if a little 'battle weary'!"
The 43-year-old newsreader never dared dream she would be a mother of two after she lost an ovary, aged 29, during an operation to remove a cyst.
"To be blessed with baby number two seems beyond a miracle," she told HELLO! in an exclusive interview ahead of the birth.
"It seems it's also beyond the doctors' understanding, too. It's simply amazing and we are so excited."
She added: "I have felt such utter joy in motherhood that I just wanted the chance to do it all over again. Despite my limited chances, I thought it was worth trying again. I just wanted to have one more try naturally and see what happened."
This time around she waited five months before sharing the news, joyfully tweeting a baby scan, in which her unborn child appeared to be giving a thumbs up.
Kate also spoke up about her experiences in order to give other couples struggling with the same issues some encouragement.