Jessica Simpson, fiance Eric Johnson and baby Maxwell in Hawaii on Christmas Eve 2012. Credit: Splash News

Jessica Simpson is making sure to keep her baby bump warm this holiday season -- even in sunny Hawaii.

The Fashion Star mentor, 32, donned her favorite green Theory sweater and a pair of fuzzy UGG boots for a Christmas Eve outing with fiance Eric Johnson earlier this week.

Simpson has worn the green poncho sweater before, pairing it with jeans, tights and barely there shorts throughout the year.

Baby Maxwell, nearly 8 months, got a lift from dad for the shoreline stroll.

One day later, on Christmas Day, Simpson officially announced her pregnancy on Twitter with a photo of Maxwell seated in front of two important words written in the sand before her: "Big Sis."

"Merry Christmas from my family to yours!" Simpson tweeted.

Simpson's mother Tina, sister Ashlee and nephew Bronx, 4, were also on hand to celebrate Christmas with her and her ex-NFL star fiance, 33.