Cavallari, 27, made the announcement on Wednesday via social media, posting a photo of baby booties, a baby hat and her hospital bracelet with the caption:
"Welcome Jaxon Wyatt Cutler 7lbs 11oz 5/7/14."
This is the second child for Cavallari and Cutler, 31, who had their first son, Camden Jack, in August 2012.
The former reality TV starlet made waves a couple months ago when she revealed they did not vaccinate Camden and don't plan to vaccinate any of their children.
"We didn’t vaccinate. I read too many books about autism and the studies,” Cavallari said while on FOX Business’ The Independents.
“There’s a pediatric group called Homestead, or Home First…they’ve never vaccinated any of their children and they haven’t had one case of autism. And now one in 88 boys is autistic, which is a really scary statistic.”