Dax Shepard and Kristen Bell

Kristen Bell and Dax Shepard welcomed a baby girl, the couple announced on Twitter Thursday.

"Lincoln Bell Shepard is here," Shepard tweeted. "She has mom's beauty and dad's obsession with breasts. Hooray!!!" Bell added: "My new roommate poops her pants and doesn't pay rent... Basically @daxshepard1 pre-sobriety :) welcome baby Lincoln xo."

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This is the first child for the 32-year-old House of Lies star and her Parenthood fiancé, 38, who announced they were expecting in November. The couple got engaged in 2009.