Jack Osbourne's fiancee is reportedly expecting a baby girl.

The reality TV star recently announced he and Lisa Stelley were having their first baby together and now sister Kelly Osbourne has revealed the gender of the unborn tot.

When asked if she was going to spoil the baby, Kelly told America's In Touch magazine: "My brother already said, 'You're not allowed to spoil her!' "

However, she tried to backtrack and hurriedly said: "Oh, I actually don't even know what it is yet, no one does."

Although he can't wait to become a father, Jack recently revealed the baby "wasn't planned".

He said: "I'm excited. It's a very good thing. It wasn't planned, if that tells you anything...

"I'm just really happy about the whole thing. It's going to be a new chapter in my life and I'm excited about it."

The 'Adrenalin Junkie' host is known for his love of extreme sports but he knows he will have to curb his wild lifestyle when he is a father.

He said: "I can't be selfish. Ultimately your priorities do shift."