Kristin Cavallari had two reasons to be in Cabo San Lucas, Mexico over the weekend.

In addition to being a bridesmaid in pal Kendhal Beal's wedding, the pregnant 25-year-old was also looking forward to spending some quality time with fiance Jay Cutler, 28.

PHOTOS: Pregnant bikini bodies

Cavallari showed off her growing baby bump in a strapless black one-piece by Cia.Maritima, featuring side cut-outs. "My stomach literally grew double overnight!" the Laguna Beach star tweeted two weeks before her vacation. "This belly came out of nowhere!"

VIDEO: Kristin Cavallari opens up about her tampon disaster

The former reality star -- who's been craving Tito's Tacos and cupcakes -- is looking forward to seeing her Chicago Bears quarterback beau become a first-time father.

PHOTOS: Kristin Cavallari's sexiest bikini moments

"He's gonna be a great dad! He's so cute with kids," Cavallari told Us Weekly in February. "He's good with my little dog, so he's gonna be really, really cute with kids!"

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