Lopez and husband Marc Anthony have kept quiet regarding persistent baby rumors in recent months.
Cavalli, who designed much of Lopez' flowing wardrobe for her current joint tour with Anthony, spilled the beans at the party to promote Roberto Cavalli Vodka at his New York showroom, People.com reported.
"Jennifer Lopez, at this moment, she requests something very special because she is waiting for the baby," Cavalli told People when asked what kinds of outfits he creates for his high-profile clients.
"It is so complicated because every week she is getting bigger," he said. "The thing about Jennifer Lopez, she is a singer, she is a dancer. ... Most of the time when I prepare something for the tour, the performer, they want something very soft so they can dance and so they can move free."
A representative for Lopez did not immediately return calls for comment, People.com said.
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