As Damien hits the table and his mother falls, just before hitting the ground, she turns around and she's laying on her stomach. In the next shot, we see her laying on her back, while some blood is dripping out of her mouth.
A few seconds later, she's laying on her belly again...
In this scene the way she screams is nothing compared to the scream where the nurse pushes her out the window. (Just put the volume up. You'll see what I mean.)