The broadcaster and her husband Mike Heron faced fertility struggles when it came to falling pregnant with their first child, daughter Clemency. And they believed having another child would be nigh on impossible.
But now, two months before their second child is due to be born, Kate, who's 43, has spoken of her delight of being able to give Clemency a sibling.
"To be blessed with baby number two seems beyond a miracle," she told HELLO!. "It seems it's also beyond the doctors' understanding, too. It's simply amazing and we are so excited."
Kate has been open about her fertility struggles in the past, having undergone several unsuccessful rounds of IVF before falling pregnant with Clemency naturally. And she reveals that following the birth of her daughter she longed to have a second child.
"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."
In the interview, Kate also reveals for the first time that she suffered two miscarriages after having Clemency – which she says despite the obvious sadness also gave her some hope that she could fall pregnancy again naturally.
It did lead her to wait however until she was five months along to announce her happy news. She says that she now hopes to provide support to others who struggle to conceive.
"I think it helps for women and their partners to be able to talk openly about what they are going through and to know they’re not alone, and that even with the tough times there can always be hope", she said.
"Mike and I struggled to have children for the last seven years. Now it feels as if we're coming to the fruition of a long but lovely journey. I would love to know that there are others out there who are able to do the same."
To read the full interview buy this week's issue, out now, or download the digital edition here.