Kristin Cavallari says that her pregnancy means it is the first time she's had sample size clothing "not fit me."

The Laguna Beach star, 25, is expecting her first baby with Chicago Bears quarterback Jay Cutler and admits she's already experiencing a change in her wardrobe.

She told Us Weekly at the Betsey Johnson fashion show in New York that she can no longer fit into some of her favourite clothes.

"So I have this thing called the Belly Band that just goes around the top of your jeans so you can wear them without buttoning them," she explained.

"It's the first time I've had sample size dresses not fit me. It's all for a good reason. It's all right. I'm pregnant."

Kristin admitted that she is "definitely giving in to my cravings" but has a plan to not spiral out of control.

"I'm trying to balance it out by eating healthy as well," the reality star said. "I'll eat a Twix and then I'll have a juice to even it out."

The former Dancing With The Stars contestant added that she hadn't decided on what she was going to call her bundle of joy yet.

"We're throwing around a couple, but nothing is sticking quite yet," she said. "After we know for sure if it's a girl or a boy, it will be easier to come up with concrete names."