"Belly's gonna get ya," Abbey captioned the photo. "#bumpvschristmaspodge."
Liverpool-born Abbey's bump looked prominent in the photo, despite only announcing her pregnancy last week.
The 28-year-old and her footballer husband Peter Crouch revealed they are expecting a second child on 16 December.
"Super excited to announce Pete and I are expecting our second baby!" she tweeted. "We couldn't be happier."
Abbey and Peter, who married in 2011 after dating for five years, already have a three-year-old daughter named Sophia.
The catwalk star, who won series 11 of Strictly Come Dancing in 2013, spoke exclusively to HELLO! last year about her time on the BBC dancing show and how it compromised the time she could spend with her daughter.
"The only downside to the show for me is being away from my daughter," said Abbey. "Im used to doing my jobs like a couple of photoshoots a month and a bit of presenting here and there, but the majority of my days are with the baby."
"So to have to put her in nursery all day," she added. "And for Pete to pick her up and it's dark when I get home and she's in bed - it's quite hard."