05/21/2012 09:16 am ET

Pregnant Kristin Cavallari Shows Off Baby Bump Before Co-Ed Shower In LA (PHOTO)

Kristin Cavallari is positively glowing!

The pregnant star tweeted a photo of herself -- growing baby bump included -- before heading out for a special baby shower in West Hollywood. According to Us Weekly, guests at the co-ed shower included Cavallari's former "Hills" co-stars Stephanie Pratt, Heidi Montag and Spencer Pratt.

Cavallari, who is expecting a baby boy with her fiance, Chicago Bears quarterback Jay Cutler, recently relocated to the Windy City and has been busy getting ready for motherhood. Though she admitted in Glamoholic magazine earlier this year that she and Cutler were surprised when they learned they were going to be parents, they couldn't be happier.

"Your motherly instincts naturally kick in," Cavallari said about learning she was pregnant. "We weren't trying to have a kid but we weren't not trying, we left it up to fate. I knew there was a possibility but I was really excited! Even if you are trying, just to see a positive result is shocking!"

For more details on Cavallari and Cutler's baby shower, head over to Us Weekly.

Check out Cavallari's baby bump below, as well as photos of other stars who are expecting:

Celebrity Babies On The Way