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Spice up your baby shower!

On Sunday, mom-to-be Melanie Brown invited several of her famous friends over for a nontraditional baby shower at her California home. Guests -- including Kim Kardashian and Denise Richards -- joined the Spice Girl's hubby, Stephen Belafonte, and her daughters Phoenix, 12, and Angel, 4, to celebrate the upcoming birth of her third child.

"It was more of a celebration [than a baby shower]," an insider told Us Weekly. "Mel wanted a party atmosphere. People were hanging out, kids were swimming."

Bride-to-be Kardashian, 30, brought her pal Brittny Gastineau to the party, while new mom Denise Richards, 40, was joined by her dad. Kendra Wilkinson's hubby Hank Baskett and their son Hank came out for the affair; Wilkinson herself, 26, was unable to attend to do a hosting obligation.

The low-key fete lasted from 12 to 6 p.m. and while beer, wine and Moet Ice were available "no one was drinking heavily," the insider said.

DJ Lindsay Luv spun songs by Michael Jackson, Prince and the Black Eyed Peas.

Brown is due "any day now," according to a source. She and Belafonte -- who has a daughter, Giselle, from a previous relationship -- "won't know what they are having until she delivers."