Duckworth: 'So many of us professional women give up our fertility'

"My gynecologist at the (Veterans Affairs) facility actually, when I first started this over 10 years ago trying to conceive my first child, said, 'You know, so many of us professional women give up our fertility -- our fertile years -- in exchange for our profession, and that needs to change,' " the Illinois Democrat told CNN's Erin Burnett in her first interview since sharing her pregnancy news.

"Well, I want people to know that it is a journey, that it is a long process," Duckworth said.

The senator said her doctor assured her at the time that it's not unusual for her to be 42 years old and trying to conceive.

"And unfortunately, that's what families are facing all over this country, and so I wanted to make sure that Americans understood that this is a journey, we can get there and we need to support families," Duckworth said.

Duckworth is a first-term senator and a retired Army lieutenant colonel who was a helicopter pilot in the Iraq War.

She announced Tuesday that she's expecting her second child in April. She will be the first sitting US senator in history to give birth while in office.

Duckworth had her first daughter, Abigail, in 2014 when she was serving in the House of Representatives.