07/15/2011 AT 07:45 AM EDT
Her father-in-law first spilled the beans
in May, and this week a revealing bikini shot
showed a baby bump, but it has taken until Friday morning for French First Lady Carla Bruni-Sarkozy to make it official.
Having already been spotted sporting maternity wear
, the 43-year-old tells the newspaper Nice-Matin
that her condition is "coming happiness, unexpected and unhoped for."
While tabloids have said the baby is to be a boy – and that she is 5½ months along – when it comes to the impending arrival's gender, Bruni-Sarkozy says, "That, I don't even know myself. There are certain things which one should keep secret."
She is equally elusive about her due date, but does reveal that her three years as France's first lady has not been a "burden" and "is much less tiring than 10 years of modeling."
She also says she has another song album in the works.
Sarkozy, 56, and Bruni wed in 2008
. Her son from a previous relationship
, Aurélian, is 10.
The French president has three sons between the ages of 25 and 13 from his two previous marriages. Last year, he became a grandfather for the first time.