The one-time Laguna Beach and Hills starlet confirmed that she's got another baby on board Tuesday via her Twitter.
"Thank you for all the love!! We are so excited for Camden to be a big brother!" the 26-year-old Tweeted today.
Camden is her first son with Jay, and just last year, Kristin said she wanted to expand her family ASAP.
"I can see us having another baby in a year," she said at the time. "We'd love to have three boys and a girl. But we'll be happy with anything!"
Two down, two more to go! But did a former MTV costar spoil the sex of the baby already?
"@KristinCav CONGRATULATIONS on having another boy!" Hills castmamte Heidi Montag Tweeted today. "You must be thrilled!!!! So excited for you and Jay! Sending my love to your family."
Too bad Kristin herself doesn't even know if they're having a boy or girl yet.
"Lol...@heidimontag jumped the gun...we don't know the sex ;)," she quickly replied.
Baby boy or girl, congrats to the happy couple!
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Gallery | Celebrity Babies