Katona and husband Mark Croft are to name their son Maxwell

Katona, 27, who is expecting her fourth child, was admitted after her midwife became concerned she had the potentially life-threatening condition.

A spokeswoman said: "In fact it was water retention and low iron levels, which brought on similar symptoms."

Katona is expected to be released from hospital soon.

"Mummy and baby are fine," her spokeswoman added.

Rehab clinic

Katona's publicist Max Clifford earlier said the singer had been in "increasing pain" before being admitted for treatment in Macclesfield on Tuesday.

He stressed that she had been taken into hospital by her husband Mark Croft as a "precautionary measure".

Katona, who won I'm A Celebrity... Get Me Out of Here! in 2004, recently ended a stay at a rehab clinic.

Filming on her current MTV reality show Crazy In Love was suspended after she was admitted to The Priory for a fourth time last week, and is again on hold.

Mr Clifford said that Katona has been receiving treatment for bipolar disorder.

The ex-Atomic Kitten singer has two daughters by her first husband, former Westlife star Brian McFadden, and already has a daughter with second husband Mr Croft.

The pair have said they will name their second child, a son, after Max Clifford.