London, Sept 19 (ANI): Pictures of Angelina Jolie with a 'baby bump' have sparked rumours that she and Brad Pitt will soon be welcoming another child into the family. However, doctors insist that she is just too thin to conceive.

A pal of the actress revealed that the 'Lara Croft' star was desperate to have another baby with her beau, but has been told by her doctors that she must put on some weight before she can get pregnant.

"Angelina is desperate to get pregnant again, but doctors say she is just too thin," The Sun quoted the pal, as saying.

The friend also revealed that the UN Goodwill ambassador had recently been convinced that she was expecting Pitt's baby, but was left heartbroken when she found out that she wasn't.

"She convinced herself she was already pregnant so was heartbroken," the pal said.

Jolie's weight plummeted after her mum Marcheline Bertrand's death earlier this year, but pals say that she has now put on a few pounds.

The star and Pitt are already parents to four kids - Maddox, 6, Pax, 3, Zahara, 2, and Shiloh, one.

Pitt recently admitted that he and Jolie were ready to take on one more child. (ANI)