Tori Spelling and husband Dean McDermott will soon have a new addition to the cast of their reality TV show.

The Tori & Dean stars have announced they are expecting their third child together this fall.

"I know there's been a lot of speculation, so I wanted everyone to hear from me... It's official... Dean & I are PREGNANT!!!!" Spelling wrote on her Twitter account on Monday.

The couple's new baby will join their son and daughter. Two-year-old Stella Doreen McDermott was born in June 2008, while their first child Liam Aaron McDermott -- who is four-years-old -- was welcomed into the world in March 2007.

Liam was born one week before the first-season premiere of Spelling and McDermott's Tori & Dean: Inn Love Oxygen reality series, and Spelling coincidentally gave birth to Stella a week before the third-season debut of Tori & Dean: Home Sweet Hollywood.

Although the Tori & Dean stars are thrilled about the pregnancy, 37-year-old Spelling plans to keep the sex of the baby a mystery. 

"We've been blessed with a boy and girl already, so this time we've decided to do it the traditional way and not find out the sex," she told People.