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Mariah Carey is keeping her lip zipped over rampant speculation about whether there's a bun baking in her oven. But Radar Online is convinced the chanteuse, who appeared to be sporting a slightly swollen belly during a weekend concert stop in Brazil, is a little more than four months along with a Nick Cannon-shaped bundle of joy.

"She's very excited," tattles a source. "She wants to wait as close to full-term as possible before going public with the news to her fans."

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Further fueling the baby talk: People magazine points out that Mariah, 41, was snapped in Sao Paulo styling a maternity dress: a brown spaghetti strap number currently on sale at A Pea in the Pod.

Retail price: a thrifty (for Carey) $139.99.

And while Radar says Nick is beside himself with excitement over the supposed stork visit and is allegedly kvelling to his inner circle, he played things cool during a radio interview on Monday.

"I've said it before, and I'll say it time and time again," he sidestepped. "When my wife feels like talking about whatever she wants to talk about, you will hear it directly from her."

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Besides, Cannon points out, "We all know it's extremely personal, and it is for a woman to deal with things with her body, and especially when dealing with the idea of childbirth and all that stuff."

Echoed Carey's rep to People, "I spoke to Mariah from Brazil. She is very superstitious -- and when the time is right for her and Nick to announce something, she will."

Still, the chart-topper did seem to offer a clue via Twitter.

"Seriously, I really do love it here [in Brazil]. Beautiful people inside and out!" she wrote on Saturday, before adding, "Tonite was tuff 4 me 4 personal reasons, but U got me thru!"

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