The former glamour model - who has sons Harvey, eight, Junior, five and daughter Princess, three, from previous relationships - and her cage-fighter husband Alex Reid are keen to have a child of their own but have now had two unsuccessful rounds of fertility treatment.
Katie - who spoke about the first course of treatment in her new book `You Only Live Once` - said: "I`ve actually done two IVFs and in that book I only talk about having one.
"But both times they didn`t work. The second time seemed to be more successful, but yet again day 12, and then you start to bleed and you think, `Is it working?` But then you get the phone call from the doctor saying it hasn`t. And it is quite traumatic on your body I must say."
Katie also admitted she found undergoing the treatment doubly hard because of the scrutiny her body received due to side-effects of the hormone injections she was taking.
She explained: "It did hurt me because in the papers at the time they said I was looking fat or pregnant and I just thought that`s really out of order. Because when you`re having injections, your ovaries expand so of course you`re going to look like you`ve got a tummy and it`s like they`re tempting fate. I felt like phoning them up and saying, `I`m going through IVF and I`m injecting myself and I`m needle phobic,` but what can you do?"
However, the 32-year-old star isn`t giving up and knows it will eventually happen.
She said in an interview on UK TV show `This Morning`: "Just because I`ve got kids, it doesn`t me I can fall pregnant with someone else and it is quite a traumatic thing, because to do IVF again you have to wait a couple of months for your body to recover from the last attempt.