Jessica Simpson has been writing lullabies to sing to her baby.

The 31-year-old singer is due to give birth to her and fiance Eric Johnson's first child this month and she has been penning her own songs to serenade her daughter with.

A source told this week's US issue of OK! magazine: ''She talks to the baby and already feels like she knows her. She sings to her all the time, too. What's really sweet is that the baby already has songs written especially for her!''

Jessica is in the final stages of pregnancy and both she and Eric cannot wait to meet their baby now and start caring for her.

The source explained: ''Jessica is going to be the most unbelievable mother - she's taken to it like a duck to water.

Jessica isn't worried about the potential parenting tribulations ahead of her because she has already had a lot of practice being an aunt to her sister Ashlee's three-year-old son Bronx and she has complete confidence in Eric's abilities as a father.

The 'Fashion Star' judge said in a recent interview: ''Eric is going to be an unbelievable dad. I can't wait to see if he can master ponytails and braids!''