No senator has ever given birth while holding office. Sen. Tammy Duckworth just changed that.

Sen. Tammy Duckworth (D-IL) is the first US senator to give birth while holding office.

Duckworth’s second child, Maile Pearl Bowlsbey, was born Monday, making Duckworth one of 10 female lawmakers who have given birth while serving in Congress. But all those women were members of the House of Representatives when they had their children, including Duckworth, who had her first child while serving as a representative in 2014.

Beyond being a milestone for the (mostly male and older) Senate, Duckworth, in a January interview she gave to the Chicago Sun-Times’s Lynn Sweet, described her struggles to get pregnant, including a miscarriage she suffered during her 2016 Senate campaign. Duckworth had her daughter at 47 while she was serving in the House, and her second child will be born shortly after she turns 50. “I’ve had multiple IVF cycles and a miscarriage trying to conceive again, so we’re very grateful,” she told Sweet.

Duckworth was first elected to the House of Representatives in 2013. She had previously worked in the Obama administration’s Department of Veterans Affairs. She served in the Iraq War in 2004 and lost both her legs after her helicopter was shot down. In 2016 she ran for an Illinois Senate seat, defeating Republican incumbent Sen. Mark Kirk.

Duckworth also talked about the challenges of taking maternity leave while representing her state in Congress. She planned to take 12 weeks’ paid leave but told Politico’s Women Rule podcast in February that she was trying to figure out a way to work with her party’s leadership so she could still participate in critical voters while she’s out. “You’re not allowed to bring children onto the floor of the Senate at all, so if I have to vote and I’m breastfeeding my child, what do I do, leave her sitting outside?” said Duckworth.