The Hills and Laguna Beach star looked beautiful while filming a segment for VH1's Morning Buzz in New York on Thursday (20 March).
Kristin is expecting her second child with husband Jay Cutler.
While the 27-year-old clearly loves being a mother to one-year-old son Camden, she's admitted that she never thought she'd become the first Hills star to start a family.
"I thought I'd be the last. I had thought it was so far from where we were, so it's not really something that [I considered then]," she told People.
"Lauren [Conrad] always seemed like she wanted to get married and have kids, so I wouldn't have been surprised if she was maybe the first one."
Kristin married American footballer Jay in Nashville, Tennessee last year, and they currently reside in Chicago.
Lauren, meanwhile, became engaged to boyfriend William Tell in October 2013.
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