"She's definitely pregnant... Miranda's thrilled," says a source close to the Australia native, who wed the actor, 33, at an undisclosed location -- reportedly in the Caribbean -- less than a month after revealing their engagement on June 21. "She's telling all her friends, mostly other models, about it."

While the pal says no official announcement will be made, the couple of three years' big news will be hard to keep hidden.

"She poses in lingerie," says the friend of Kerr, who has modeled for Victoria's Secret since 2007. "It will be obvious soon enough."