Mariah Carey is obsessed with pregnancy books.

The 'Hero' singer - who finally confirmed last week she is expecting her first child with husband Nick Cannon - is determined to do as much preparation for motherhood as possible and has completely changed her eating habits.

A source told gossip website Absolute Now: "Mariah has turned ultra health conscious. There is nothing unhealthy in the house. No junk food, no alcohol, nothing. Nick is making sure she has everything she needs including fetching her just about every book on babies and pregnancy ever written. Mariah is 41 and she's leaving nothing to chance."

Nick recently revealed he is doing his best to persuade his wife to ditch her favourite high-heeled shoes in favour of something more comfortable during her pregnancy, but has so far had no success.

He said: "I come home yesterday to help my wife get ready for her video shoots and she has these 19-inch heels on. So I go into the closet searching for some flats for my wife . She got a lot of damn shoes - it's like a Macy's. And Mariah Carey does not own one pair of flat shoes."

However, Mariah defended herself, insisting she does own flat shoes - but did not want to wear them.

She said: "To be fair, I had some boots from Aspen, some Dior boots. Ski boots.

"And then we did find some flats and then they were a regular ballet slipper, like a beige, and I was like, 'I don't think so.' "

After persuading his spouse to don ski boots, the 30-year-old presenter is now planning a shopping trip to buy the singer some more practical footwear.

He told her: "Basically, I got Mariah Carey, the high-heel Queen, to put on some flats. And this is amazing. I'm going shoe shopping today, needless to say, to buy you some flat shoes."