Pregnant and proud: Angelina unveiled her baby bump at the Independent Spirit Awards last month [Agencies]

Brad Pitt and Angelina are also adoptive parents to Zahara, three, Pax Thien, four, and have a biological daughter Shiloh Nouvel, 21 months.

In preparation for the birth this summer, Pitt has been rescheduling his work so he has enough time to spend with Jolie and the children.

A friend of the couple told the Mail Online: "They're having twins, Angelina is healthy, and he's thrilled that he's going to be a father once again.

"Brad's telling everybody close to him, because he's having to change around his work schedule to get ready for the birth.

"They didn't exactly plan this pregnancy, but they wanted more children and Brad says Angelina was very willing to have them herself."