ACTRESS Demi Moore wants to become a mum with her second husband Ashton Kutcher.

The 44-year-old, who already has children aged 18, 15, and 13 with first husband Bruce Willis, said: "Once you hit three, it's like, What's the difference between three or four or five?'"

Of her relationship with Kutcher, 28, Moore added: "I think it caught us both by surprise, particularly him."