Beyonce Knowles is set to open up about her decision to hide her baby bump from the media in a revealing new documentary about her life. The 31-year-old American singer has offered a video from her pregnancy in a new teaser for the HBO film, which includes an intimate black and white footage of her belly. “I always battle with how much I reveal about myself,” Contactmusic quoted her as saying. Beyonce confirmed the baby news at the MTV Video Music Awards in August 2011, with a simple belly rub on the red carpet and another during a performance at the ceremony.