Pitt, who is promoting his new movie The Assassination of Jesse James by the Coward Robert Ford at the Italian event, admits he and Jolie are "ready" for another kid.
They are already adoptive parents to Cambodian Maddox, 5, Vietnamese Pax Thien, 3, Ethiopian Zahara Marley, 2, and are biological parents to 15-month-old Shiloh Nouvel.
The 43-year-old also described how much he enjoys being a father of four.
He said, "It's the most fun I've ever had and also the biggest pain I've ever experienced. I love it and can't recommend it any more highly, although sleep is nonexistent."
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