The former glamour model - who already has three children from previous relationships - is expecting her fourth child with husband Kieran Hayler.
The couple married just five weeks ago and Katie admitted her pregnancy was a shock, telling the Sun on Sunday: "It comes as a shock. But we`re all over the moon.
"I`d be lying if I said I wasn`t nervous because I`ve experienced miscarriages in the past." Katie, 34, and Kieran, 25, tied the knot after a whirlwind two-month romance but she previously insisted she doesn`t care what anyone thinks about their union.
She said: "I know my marriage to Kieran is going to attract criticism and that there will be people selling stories on the back of their perception of me and my decision. I will take that criticism on the chin and argue my corner where I feel it is necessary.
"As usual, I get a hard time for my choices because I`m me - I still don`t really understand why. "This is only my third marriage. I did my own Pricey Marriage Survey and discovered I was in good company. Joan Collins has been married five times, Liz Taylor did eight and Zsa Zsa Gabor nine. "So there! I get stick, but no one has picked on them for all the marriages they`ve had."
Katie - who has children Junior, seven, and Princess Tiaamii, five, with first husband Peter Andre, as well as 10-year-old Harvey from a relationship with Dwight Yorke.
She was also married to cage fighter Alex Reid and split from her last fiance Leandro Penna in October.