Rihanna shocked the world Sunday by announcing her pregnancy during her Super Bowl performance -- but it was a well-kept secret even among people who were part of the show.
Super Bowl sources tell TMZ ... none of her backup dancers -- upwards of 280, as we came to find out -- had any idea RiRi was preggo before she hit the stage this weekend, and that's due in part to the baggy clothing she'd been rocking during all the rehearsals.
Our sources tell us Rihanna was wearing very loose-fitting outfits both on Saturday and on Sunday as she was practicing her set.