Mrs Bruni-Sarkozy, as she is officially known, is currently on holiday in the presidential residence at the Fort de Brégançon.
Speaking to local newspaper Nice Matin, she said that the job of first lady is "not a burden. It is a role that has its duties, but nothing too overwhelming. My husband has the real workload and I am there to accompany him. It's a responsibility and one has to be careful what one says".
Bruni has tended to keep a low profile in France since she married Sarkozy in 2008, only rarely giving interviews. Her glamorous background as a model, singer and actress has sometimes seen her criticised for being out of touch with ordinary French people. She insisted in the interview that she is "not an airhead".
Speaking of the pregnancy, which has been the worst-kept secret in France for months, she said it had given her "great happiness" even if it was "unexpected and not planned". She said that rumours she is having a boy were misplaced. "I don't even know myself," she said.
Bruni is making the most of the luxurious presidential residence on the Mediterranean where she is looking forward to spending most of August with her husband. She admitted she "hasn't lifted a finger". She credited the "magnificent and very comfortable" interiors to former first lady, Bernadette Chirac.
Other plans have been put on hold since her pregnancy. She has not finished her latest album and was not able to attend the Cannes premiere of the Woody Allen film, 'Midnight in Paris', in which she plays a tourist guide.
In a further hint that President Sarkozy will certainly run for re-election in 2012, she confirmed that she would like him to run "for the good of France".