The former Laguna Beach and Hills star confirmed this week that she and fiancé Jay Cutler are expecting their first child together later this year.
However, some fans pointed out that she tweeted earlier this month: "Mexican and margs in chi town with some of my fav people (sic)."
The ex-Dancing with the Stars contestant explained to followers on Monday: "I tweeted that I had margaritas a few weeks ago to throw ppl off cuz I had gotten a couple tweets about my pregnancy. I didn't really drink!"
Cavallari added: "Thanks for all the sweet messages! We are so excited for this little bun in the oven :)"
NFl star Cutler also thanked fans for their well-wishes, saying: "Thanks for all the tweets. We couldn't be more excited."
He also clarified recent reports that the couple had separated briefly last year, writing: "We don't usually comment on our relationship but for the record I never broke up with Kristin.
"It's unfortunate some people are saying hurtful things during such a joyous moment in our life."
> Heidi Montag, Audrina Patridge congratulate Kristin Cavallari on baby news