The 44-year-old No Doubt singer, who confirmed that she was pregnant with a baby boy last week, dressed head-to-toe in black as she took the snapshot.
Gwen stood before a full-length mirror to take the photo and looked stylish in black leggings and strappy heels, although she later told fans that she was wearing "inappropriate" footwear!
Taking it all in her stride, she wrote: "Bump it #allblack #inappropriateshoes #capturethemoment #miracle gx."
We bet Gwen and husband Gavin Rossdale can't wait for their new arrival. The couple, who have been married for 11 years, are already proud parents to two boys, seven-year-old Kingston and five-year-old Zuma.
Gwen told fans via an Instagram post on Friday that she was expecting her third son with Gavin. Wearing a bejewelled crown in the photo, the 'Hollaback Girl' hitmaker said: "I was ready to hand over the crown. but I guess I am still queen of the house. #itsaboy #surroundedbyboys."
Check out more stars who have announced pregnancies this year:
Copyright: WENN Lexie Appleby/Future Image/Bridow/Instagram