Kristin Cavallari will find out the gender of her un-born baby on Christmas Day.

The former 'The Hills' star, who has a 16-month-old son, Camden, with her Chicago Bears quarterback husband Jay Cutler, revealed in October that they expecting their second child and has come up with a unique way to confirm the baby's sex under the tree next Wednesday (25.11.13).

The 26-year-old blonde beauty told Bethenny Frankel's talk show 'Bethenny': ''We find out [the gender] really soon. I'm gonna have my doctor write it on a piece of paper, and we're gonna open it on Christmas together.''

The shoe and jewellery designer also discussed faking relationships, including a romance with Brody Jenner, during her days on reality TV, but insisted she is good friends with one of her old co-stars, Heidi Montag, in real life.

She said: ''I have to say, Heidi is one of the sweetest, nicest girls I think I've ever met. She has such a good heart, and I really mean that. I think she just got caught up in all the hype, which is easy to do. I mean, I get it. When I was 18, I probably got caught up in the hype a little bit, too. But she's still the same person inside. I still talk to Heidi all the time.''

But she added: ''I faked relationships, faked fights. I don't care anymore - I can tell you. At this point, it's been so many years.''