The pair started dating last year after both Atomic Kitten and 5ive reformed and hit the road for The Big Reunion tour.
‘It's a complete miracle,' says 31-year-old Natasha, before adding: ‘I've had the worst morning sickness ever.'
‘After the first scan I could breathe - Ritchie went into panic mode,’ the Atomic Kitten star revealed.
Though the couple are now unexpectedly expecting, they say that there are no wedding plans as of yet.
‘We've talked about marriage before - but there's no rush,' the couple revealed to a UK magazine.
Ritchie, 34, who moved from Australia to the UK for The Big Reunion tour, is looking forward to becoming a dad.
‘I want to be a hands on dad,’ he says. ‘Tash will be feeding the baby and I'll be feeding her sandwiches.’
'Natasha's stuck with me forever now, no matter what happens.'
Natasha is already mum to Josh, 10, with ex Fran Cosgrove and Harry, 8, from her relationship with dancer Gavin Hatcher.
The singer split from ex husband Riad Erraji last year after 6 years. The former couple are also parents to 3-year-old Alfie.