Angelina Jolie and Brad Pitt are thrilled to be adding two more daughters to their rainbow brood. But serious medical problems — and a frightening collapse — are casting a dark cloud over their baby joy.

Angelina and Brad will be adding two more girls to their growing family when Angie gives birth in July, Star has learned exclusively. And they are ecstatic at the news that they are having twin daughters. “Brad can’t wait — he absolutely adores little girls,” says a family insider. “And Angelina just loves seeing him and the other kids so excited and happy.”

But behind all the joy, Angelina’s difficult pregnancy has the superstar couple on edge, as they prepare for a worst-case-scenario birth early this summer.

In fact, just before leaving for France, Angelina suffered a terrifying collapse that left her tearful, weak and panic stricken, fearing her fall may have harmed her two unborn babies, an insider tells Star.

“Angie got out of bed and was halfway across the room when she passed out and fell,” says the insider. “Brad heard her hit the floor — hard — and he rushed to her side. She came around pretty quickly, and the medical team that has been traveling with her, a doctor and a nurse, got her back into bed and started checking her vitals.”

In March, Life & Style reported that Angie is also going to have fraternal twins, a boy and a girl. I guess we'll just have to wait and watch whether she gives birth to two girls or a boy and a girl!