Charlotte was born with brain, lung and kidney damage

Darren and Debbie Wyatt, from Portsmouth, told the BBC that two pregnancy tests had come back positive.

Mr Wyatt, 33, said: "We have only just found out last night. We haven't had it approved by a doctor yet."

The news came on the day after the High Court renewed an order allowing doctors to let 18-month-old Charlotte die in peace if she stops breathing.

It's been really stressful but I suppose it's a case of you have to cope Debbie Wyatt

Mr Justice Hedley said on Thursday that the new order was open-ended and remained subject to review.

Doctors said Charlotte has "no feelings other than continuing pain", and earlier the court had heard how experts believed her life was "intolerable".

But the Wyatts believe Charlotte is improving.

The couple said they would fight on and Mrs Wyatt added: "The next stage is the Court of Appeal, then, if we don't win that, it's the European Court of Appeal."

Mr Wyatt admitted it has been a difficult time: "It's been really stressful but I suppose it's a case of you have to cope.

"You can't just push it aside and let it get to you, you have to keep battling on."