Kristin Cavallari has given birth to a baby boy.

The reality star and her fiance Jay Cutler welcomed baby Camden Jack Cutler to the world yesterday morning and the proud mother took to Twitter to announce the couple were "thrilled" with the arrival of their first child.

"We are thrilled to welcome Camden Jack Cutler into the world. He was born this morning weighing 7lbs 9oz. Everyone is doing great!" she wrote.

The 25-year-old blonde - who is best known for being the bad girl of MTV reality shows The Hills and Laguna Beach - got engaged to Chicago Bears quarterback Jay in November 2011 for the second time. The pair previously called off their engagement in July 2011, just three months after they had originally announced their plans to wed.

Kristin surprised fans in January by announcing the news of her pregnancy. "We are thrilled to announce we are expecting our first child together. It's an amazing time in our life and we can't wait to meet the new addition to our growing family," the couple said at the time.