Jack Osbourne has revealed that his fiancée is pregnant and that they're expecting their first child together. 

The star recently announced his engagement to actress Lisa Stelly and has now explained that he is also due to be a father in the near future. Speaking to CNN's Piers Morgan, Osbourne said:

"I guess I do have something to tell you, I am about to be a father. I'm excited. I'm a little nervous."

His sister, Kelly, also wrote about the great news on social networking site Twitter and expressed her excitement at the thought of becoming an aunt:

"Girls night in w/my future sister-in-law & mother of my niece/nephew we are so happy the news is out so I can talk about it..."

"Been waiting 2 say this for so long I'm the happiest girl in the world I'm going to be an auntie! welcome 2 the family."

Watch Osbourne talk about his self-directed documentary on his famous father, Ozzy, here: