The unidentified source said Ryan, 39, who plays human resources staffer Holly Flax in the NBC series, is expecting the child with her fiance, comedy writer Eric Slovin, People.com reported Friday.
In addition to her role on "The Office," Ryan has appeared on TV series such as "The Wire" and "Law & Order," along with movie roles in "Gone Baby Gone," Dan in Real Life" and "Changeling."
Ryan's role in "Gone" earned the actress a best supporting actress Oscar nomination in 2007.
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