The former S Club 7 singer and her husband Alex Bourne welcomed their daughter Amelie in November. Stevens introduced the baby in a shoot with OK magazine.
"The whole experience is overwhelming," she said. "I can't believe we're Mummy and Daddy - proper grown-up stuff!"
The 32-year-old, who came second in the 2008 series of Strictly Come Dancing, revealed that she does not have much baby weight to lose.
"I want to get back into shape so I'm looking forward to getting back out training," she said. "I exercised right up until the last week. I've put on weight but not masses. I was lucky."