Six months pregnant Katie, 34, is due to have a Caesarean at the private Portland Hospital, central London, in three months. The baby is her second with husband Kieran.
But friends are worried about her health because of the stress of discovering the affair between Kieran and mum-of-two Jane Pountney.
A friend told The Sun: "Katie is terrified about the birth and despite everything that has gone on, still wants Kieran there."
Katie, who only gave birth to Kieran's son Jett last year, is keen not to go through the birthing experience on her own.
The friend said: "He's been a fool but it's still his child and she doesn't want to go through childbirth alone.
"Jett's birth was a traumatic experience so there's not a chance she wants to go through that on her own."
Katie also fears that the strain could harm the unborn child.
She told friends: "With this amount of stress I could go into labour or even lose the baby."
The split is also said to be affecting her sleeping and eating habits.
A friend said: "Everyone is very worried about Katie's state of mind. Normally she'd get through something like this by partying, but she can't as she's pregnant."
In other KP news, it has emerged that Kieran and Jane fell for each other because Katie over-shadowed them.
It's reported that Kieran was fed up with living in the shadow of Katie's ex Peter Andre after she gave an interview saying she wished they'd never got divorced.
Meanwhile, Jane was said to have turned against Katie after becoming fed up with the way she treated her.
A family source said: "She was sick of never getting a thank you."
She is also mum to Harvey, 12, her son by footballer Dwight Yorke, Junior, nine, and Princess, seven, her children with ex-husband Peter Andre.