Reproductive rights garnered attention during the first set of Democratic debates, held in June. It was a month after Georgia became the fourth state to pass a so-called fetal heartbeat bill, which outlaws abortion as early as six weeks into a pregnancy, when an ultrasound may be able to detect the pulsing of what will become the fetus’s heart. Multiple candidates pledged to fight the moves to limit access to abortion, and to defend the Supreme Court decision that protects it.

In the second set of debates, the candidates wrestled with the wage gap, discussing Ms. Harris’s equal pay plan. The entrepreneur Andrew Yang steered his answer on universal basic income to address sexism and harassment in the workplace.

Indeed, protecting and expanding reproductive rights has been a key issue throughout the sprawling Democratic primary. Senator Kirsten Gillibrand of New York, who appeared in the first two sets of debates and who dropped out of the race last month, focused her candidacy on championing women’s equality. In June, Planned Parenthood hosted a candidate forum dedicated largely to the topic of reproductive rights; 19 candidates attended, including nine of the 10 onstage Thursday night.

Toward the end of the debate Thursday, the three women on the stage — Senators Amy Klobuchar of Minnesota, Elizabeth Warren of Massachusetts and Ms. Harris — discussed motherhood and their careers. Ms. Klobuchar told a story about how she had been forced to leave a hospital as a new mother after 24 hours, and explained that she had fought for a law that would guarantee longer stays. Ms. Warren recalled how, years ago, she had lost her job as a special-education teacher upon becoming pregnant. And Ms. Harris discussed the influence of her mother and the barriers she had broken by winning public office as a black woman.