Ciara, 31, partially covered up the cheeky underwear with a pair of denim overalls, but her baby bump still took center stage.
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“Loved working with @CalvinKlein on this special project! #mycalvins #ad,” she wrote.
She also showed off the look on Snapchat, posing and telling watchers the same message.
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In November, Ciara said she was “feeling great” after the early months of her pregnancy were categorized by morning sickness.
She said, “You gotta totally push through it and be strong. When I’m working I don’t feel anything at all. I forget there’s a baby in my stomach. When I’m working, my adrenaline keeps me going, and I feel good.”