Angelina Jolie has dismissed speculation her pregnancy with daughter Shiloh was unplanned, after she previously insisted she wouldn't have a biological child.

Jolie adopted Cambodian orphan Maddox in 2002 as her marriage to Billy Bob Thornton was falling apart and was happy to raise him as a single mother.

In 2002, Jolie said, I'm drawn to kids that are already born. I think some people are meant to do certain things, and I believe I'm meant to find my children in the world somewhere and not necessarily have them genetically."

However, after meeting current partner Brad Pitt and adopting a second child, Ethiopian-born Zahara Marley, Jolie began to ponder becoming a mother biologically.

She tells Reader's Digest magazine, "Before I met Brad, I always said I was happy never to have a child biologically. He told me he hadn't given up that thought."

"Then, a few months after (Zahara) came home, I saw Brad with her and (Maddox), and I realised how much he loved them - that a biological child would not in any way be a threat. So I said, 'I want to try.'"

Jolie gave birth to Shiloh Nouvel in Namibia last May.