Anna Faris' four-month-old son is a ''ball of joy''.

The 'What's Your Number?' actress and her husband Chris Pratt were worried when Jack was born over two months premature but after spending the first month of his life in hospital, the baby is now healthy and at home with his proud parents.

Chris, 33, told People: ''Oh, God, he is just ... he's amazing. I love him so much. He's just a ball of joy. He's terrific.

''He was born nine weeks premature, so we spent a month in the intensive care unit with him.

''But he's totally healthy now. He is just so perfect and I love him so much.''

Anna - who was once married for three years to Ben Indra - previously revealed her mother Karen had been pestering her and 'Zero Dark Thirty' actor Chris for ''some time'' to have children so she could become a grandmother.

She said: ''Chris and I both want a family. Mum has been saying to me for some time, 'You had better start soon.' ''