Sen. Tammy Duckworth will be the first sitting senator to give birth in U.S. history, according to the Chicago Sun-Times.

"I am proud to have her as my Illinois colleague and prouder still that she will make history by being the first U.S. Senator to have a baby while in office. I couldn't be happier for her."

— Sen. Dick Durbin

There have been 10 sitting members of Congress to give birth. Three of them went on to be elected to the Senate.