08/14/2009 at 04:20 PM EDT
Amy Ryan's next role? Mom.
The actress, 39, is expecting her first child with fiancé Eric Slovin, a comedy writer, her rep confirms to PEOPLE. The baby is due in October, says a source close to Ryan.
Ryan, who was nominated for a best supporting actress Oscar for her turn as a troubled mom in 2007's Gone Baby Gone, has lately starred on NBC's The Office as human resources staffer Holly, who had a romance with Steve Carell's Michael last season.