Tori Spelling Keeping Baby No. 3's Sex a Surprise

By Sarah Durham Wilson

04/12/2011 at 11:45 AM EDT

Tori Spelling just announced her third pregnancy – and this time around, she wants to do things differently.

The Tori & Dean: sTORIbook Weddings star says she and hubby Dean McDermott want to keep the sex of their baby a surprise.

"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," Spelling, 37, tells PEOPLE.

PHOTOS: The Spelling-McDermotts Family Photo Album

Already mom to son Liam, 4, and daughter Stella, 2½, the reality star says her new addition will be joining an already boisterous brood.

"They are best friends but they are at that age where there's that love-hate relationship," Spelling told PEOPLE at the GLAAD Media Awards in Los Angeles recently. "[Liam] beats [Stella] up, and she just adores him."

But by nightfall, all is forgotten. "They want to sleep in the same room," Spelling said. "That's their new thing."

• Reporting by MICHELLE WARD and ULRICA WIHLBORG