A spokesperson for the pair, who are already parents to son Wilf, one, confirmed the happy news exclusively to HELLO! magazine, saying 'Mum and baby are doing exceedingly well and everything went as planned. Natalie, Owain and Wilf are over the moon at the new addition to the family.'
Natalie and Owain have chosen to name their new arrival Willow Mirela, and there's a touching story behind their choice of middle name.
Mirela was the name of a Romanian orphan Natalie met whilst making the Channel 5 documentary, The Lost Orphan: A Home For Mirela, who sadly passed away after filming.
Natalie pictured during her pregnancy in June 2016
The 37-year-old also shared the first picture of her daughter with her 33.7k Instagram followers, writing alongside, 'Wilf's little sister has arrived! #siblinglove 'My love has no beginning, my love has no end...No front or back, and my love won't bend...I'm in the middle lost in a spin loving you''
The couple announced that they were expecting again back in January, telling HELLO! magazine that getting pregnant again so soon came as something of a surprise.
'I can't believe that so soon after having Wilf I am pregnant again!' Natalie exclaimed. 'I feel so lucky and blessed. I always wanted a little brother or sister for Wilf, but didn’t expect to get pregnant so quickly!'
'I only did the pregnancy test to rule it out because I honestly thought…this can't be why I'm feeling a bit funny! When I saw it was positive, I nearly fell off my chair!'
In the same interview, she also revealed that she had been expecting two babies, but lost one during the early stages of her pregnancy.
'It's nature's way and it is sad. My dad put it in a lovely way and said: 'One has made way for the other.''
However, despite the heartache, Natalie added that she was loving life as a mother.
'I am just loving being a mum,' she said. 'This last year has been the best of my life, now we've got another exciting year to come. I couldn't be happier.'