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. "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)" she wrote on Twitter.

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