In a statement from her office, McMorris Rodgers, 44, the fourth-ranking House Republican and a rising GOP star, said that she and her husband, Brian Rodgers, had been hoping to be able to have another child.
She said, "So it is with great joy we announce that we are expecting our third in December."
McMorris Rodgers added in the statement that she looks forward to continuing as conference chair and running for reelection next year to her congressional seat in eastern Washington state.
She most recently gave birth to her daughter, Grace, in 2010. In 2007, the couple had their first child, Cole, who was born with Down syndrome.
"Both Cole and Grace were born while I was a member of Congress, so we will continue to balance the challenges of parenting young children and workingjust like countless moms and dads all across America," the congresswoman said in her statement.
"Your continued support and prayers are greatly appreciated," she added.