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

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

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

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.