"They weren't planning on announcing, but she hasn't stopped working," the magazine quotes a source, referring to Carey's current role in the play Skylight. "Everybody around her is being very supportive. The show ends soon and they're going back to England after."
Carey did keep her burgundy Balenciaga gown loose-flowing around the stomach area Sunday night at the Tony Awards, where she was nominated for Best Performance by an Actress in a Leading Role.
The Suffragette actress has been married to the Mumford & Sons frontman since April 2012. This will be the first child for the both of them.
"Like anyone, you try and split your time evenly …" Carey told Vogue about their super-private marriage. "Marcus is the only thing that's mine that I can keep totally away, so I try to."
But one star who had no issue recently dishing on the talented couple's relationship is their close pal, Sienna Miller.
"They both come from very solid families and have a real sense of the life they want to live," she told Vogue in April. "They have chickens and a dog, and roasts and friends, jams by campfires. It's sort of idyllic. Marcus can headline Glastonbury and Carey can be nominated for however many Oscars, and then they come back to their farm, and they're in big woolly jumpers and funny hats, raising piglets. It's an amazing balance they've managed to strike. I can't wait for a little baby to come along."
Looks like Sienna got her wish sooner than expected!