The baby - due in six weeks - will be Bruni-Sarkozy's second child. She has a son, Aurelien, born in 2001, with ex-boyfriend Raphael Enthoven.
"The baby will be viable at any time from October 1," the former model told French newspaper Le Parisien.
"Aurelien arrived on time, which means this could be a long wait, but I really do want this child so much."
Friends of Bruni-Sarkozy told the paper that because she was having a baby after the age of 40, her doctors had urged lots of "rest and clean-living".
The French First Lady has also insisted she would not release photos of the new baby, saying it's "a totally private event".
However, France's Marianne news magazine suggested the birth was ideally timed for Sarkozy's re-election campaign next year, describing the baby as the "perfect marketing tool" for the 55-year-old president.
- DAILY MAIL