Sen. Tammy Duckworth, D-Ill., is pregnant and will become the first sitting U.S. senator to give birth. Duckworth is with her daughter, Abigail, during a ceremonial swearing in by Vice President Joe Biden on Jan. 3, 2017. ( AP file photo)
Sen. Tammy Duckworth, D-Ill., is pregnant and will become the first sitting U.S. senator to give birth. Duckworth is with her daughter, Abigail, during a ceremonial swearing in by Vice President Joe Biden on Jan. 3, 2017. ( AP file photo)