Beyonce will open up about her decision to hide her baby bump from the media in a revealing new documentary she directed about her life.

In a new teaser for the HBO film, the new mum offers up footage from her pregnancy, including intimate black and white footage of her belly.

She says, "I always battle with how much I reveal about myself."

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.