Hilary Duff has posted the first picture of her baby on twitter.

The singer-and-actress shared an image of two-week old son Luca Cruz's feet on the social networking site, saying he has her ''favorite little feet''.

Hilary - who has Luca with husband MIKE COMRIE - has also returned to her exercise regime, taking up pilates and leaving her young baby with her mother.

Hilary added on twitter: ''Did a little Pilates today.Felt so good to stretch!Little man had a visit with grandma and did so well! I'm lucky to have my fam so close :)(sic)''

The 24-year-old beauty - who is best known for starring in TV series 'Lizzie Maguire' as the titular character - has previously said on twitter she was in love with her baby boy and was surprised she had got through the birth.

She wrote: ''He is the most wonderful, sweet, adorable baby.

''Wow, I can't believe I have a baby! Thank you for all the messages and well wishes. I love you all so much.''