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Baby bumpin' at the beach! Pregnant-again "Hills" alum Kristin Cavallari showed off her toned backside in a strappy black swimsuit while walking on the beach with husband Jay Cutler and 18-month-old son Camden.

PHOTOS: Kristin's life as a mom

The sweet Instagram pic shared Thursday, Feb. 27, features the family in a tropical palm-tree lined locale walking along a sandy path leading to the sea. Both parents protectively flank their little one on both sides -- the Chicago Bears QB in dark swim trunks and his wife in a sexy swimsuit by Mikoh.

PHOTOS: See Kristin's stylish pregnancy

"Been having a beautiful, relaxing family va-cay," Cavallari shared beside the filtered photo, while thanking the brand for the "perfect preggers bathing suit."

As the designer announced on Feb. 1, Cutler and Cavallari are expecting another son. "I love having a boy. So I honestly don't care," Cavallari told Us back in December as she gushed over her son.

PHOTOS: Kristin's best bikini moments

"He started walking at ten-and-a-half months," she shared of his latest milestones. "He's starting to talk and he can say a few things. He's making animal noises, which is really funny."

Between hitting the gym and designing shoes for her Chinese Laundry collection, the pregnant star has also been spending time prepping her little one to become a big brother. "He's a little too young to understand that I'm pregnant and we're having another baby," Cavallari dished. "I think the closer we get, the more he will understand."

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