Jessica Simpson [1] has confirmed the obvious - she's having a baby.

The 31-year-old entertainer tweeted a photo of herself [2] Monday dressed as a mummy for Halloween, holding her baby bump with the words, "It's true. I am going to be mummy."

It will be the first child for Simpson and her fiance Eric Johnson. The two announced their engagement last year.

Beyonce's Baby Bump & 13 More Pregnant Pop Stars [3]

Her pregnancy has been rumored for weeks, and recently, photos of Simpson - with a bulging bump - have appeared.

Pregnancy won't slow Simpson down. She's signed up to be a mentor on the upcoming NBC reality show "Fashion Star" alongside Nicole Richie.

© 2011 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.