The 39-year-old red-carpet host and her model boyfriend Clark Mallon are thrilled to finally be able to share their happy news, reported Hello! magazine.
"It has been quite hard to keep it under wraps. We haven't told many people. It's going to become so much more real when everyone knows. We were trying to get pregnant so this is the best news ever," she said.
Mallon, who's from North Wales, added, "To start with it was quite a lot to get my head around - it's such a life-changing event - but now I can't wait to be a dad and start my family with Terri. She has just started to show and it's very exciting."