Story highlights Sen. Tammy Duckworth is one of only 10 women who have given birth while in Congress

Duckworth is a retired Army lieutenant colonel who was a helicopter pilot in the Iraq War

Washington (CNN) Sen. Tammy Duckworth will make history when she becomes the first sitting senator in history to give birth later this year, her office said Tuesday.

The Illinois Democrat announced she is expecting her second child in the spring.

"Bryan and I are thrilled that our family is getting a little bit bigger, and Abigail is ecstatic to welcome her baby sister home this spring," she said in a statement. "As tough as juggling the demands of motherhood and being a Senator can be, I'm hardly alone or unique as a working parent, and Abigail has only made me more committed to doing my job and standing up for hardworking families everywhere."

She is one of only 10 women who have given birth while serving in Congress. Her office told CNN she is due in late April.

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