Klass, who took no break from work while she was an expectant mum, was returning after co-hosting BBC topical magazine programme 'The One Show' when she went into labour.
"(She) felt a bit weird on the way home. She went to the hospital to get checked and they told her she was in labour. Her stint on the show is obviously over," Hello quoted the spokesman, as saying.
This was Klass' and beau Graham Quinn's first child and the couple has named her Ava.
The 29-year-old's spokesman revealed that the mum and baby were doing fine.
"Myleene had a problem-free labour, and mother and baby are doing well," the spokesman said.
"She and Graham are ecstatic," he said.