U.S. Sen. Tammy Duckworth is set to make history as the first senator to give birth while in office.

Duckworth, 49, announced Tuesday that Northwestern University’s fertility unit was seeing her through her second pregnancy. She joked withthe Chicago Tribuneabout her status as a “geriatric mother,” saying: “I don’t let that bother me though. I think 50-year-old moms are the new 40-year-old moms.”

Duckworth, who defeated Republican Sen. Mark Kirk in 2016, is expected to deliver in April and although she’ll be the first sitting U.S. senator to give birth,10 congresswomen in the U.S. House– including Duckworth – have given birth while in office.

The Centers for Disease Control and Prevention has documented an increase in the average age of pregnant women in recent years. In 2016 – for the first time – the federal agency reported more births in the U.S. by women in their early 30s than by younger women. The margin was extremely slim, however.

That year, the CDC listed the U.S. birth rate for women ages 30-34 as 103 per 1,000; and the rate for women ages 25-29 as 102 per 1,000.

Pregnant women who are older have a higher risk for premature delivery, miscarriages, gestational diabetes and chromosomal abnormalities in babies such as Down syndrome, according to the Mayo Clinic.

But older fathers may also pass risks onto their children. A2014 study in the Journal of the American Medical Associationfound that children born to fathers ages 45 and older are at a higher risk of psychiatric problems such as autism, schizophrenia and bipolar disorder, compared to the offspring of fathers in their early 20s.

Dr. Wendy McDonaldis a board-certified obstetrician-gynecologist withWomen’s Health Consulting, a private practice under Northwestern Memorial Hospital. She expresses herself creatively through her websiteDr. Every Woman, where she posts entertaining and educational videos, blogs, comics and more.

She joins “Chicago Tonight” to discuss the topic of pregnancy later in life.

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