House Speaker Nancy Pelosi (D-Calif.) celebrated the start of the 110th Congress on Jan. 4 with members’ children and grandchildren, including some of her own. (Rich Lipski/The Washington Post)

On Thursday, Sen. Kirsten Gillibrand (D-N.Y.) and Rep. Rosa L. DeLauro (D-Conn.) reintroduced the Family and Medical Insurance Leave Act, a proposal to guarantee 12 weeks of partially paid leave, in contrast with the current unpaid FMLA leave policy. In speaking with HuffPost, DeLauro said that the bill has a chance because this new Congress includes the largest numbers of women and young people it has ever seen.

But there’s one group of members of Congress whose record numbers haven’t been as widely discussed: women in Congress who have children younger than 18 while they are serving in office, a group we refer to as “working moms.” This group nearly doubled its numbers to 23, with 21 serving in the House and two in the Senate. Newly elected Rep. Katie Porter (D-Calif.), for example, is a single mother of three with children ages 12, 10, and 7; Rep. Angie Craig (D-Minn.), who is the first lesbian mother in Congress, has a son still in high school. Recognizing their growing numbers, Rep. Debbie Wasserman Schultz (D-Fla.) has worked on creating a “Moms in the House” caucus, which recently had its first informal meeting.

This influx of mothers is likely to influence legislation being considered by Congress. Here’s how.

This is how we did our research

Our study examined differences in bill sponsorship of working mothers with children younger than 18, compared with mothers of adult children and to women without children. To determine which lawmakers fit which group from the congresses between 1973 and 2013, we used biennial issues of the Congressional Directory as well as contemporary news coverage of congressional members.

Over that 40-year period, there were 196 female members total, with 158 who were parents. Of the mothers serving in the House, 121 had children older than 18. Only four had children younger than 18 in 1973. Until 2018, the number of women in the House with no children or minor children remained fairly steady, while the number with adult children grew steadily. While this study focuses exclusively on differences among women, we are conducting ongoing research on the nearly 1,700 men who served in Congress during this same period

To determine whether there were different policy priorities among these 196 female members of Congress by parental status, we examined five Library of Congress issue categories on Congress.gov (education, crime and law enforcement, families, labor and employment, and health) to identify all bills introduced by female lawmakers on issues. From those, we created a data set specifically of bills related to children and families, including such issues as crimes against children, preschool through secondary education, child care, adoption and foster care, parental leave and child labor.

So far, here’s what we found.

1. Working mothers sponsor family-focused bills more often than other women

On average during the period we study, women in Congress introduced about 25 total bills in each session of Congress. Controlling for other forces that influence lawmakers’ tendencies to sponsor bills (such as how long they’ve served and their ideological bent), mothers of children, of whatever age, write more bills focused on issues relevant to children and families than do women without children. Each year, women without children are the primary sponsors of nearly seven child-related bills, while working mothers write and introduce more than eight.

These differences may seem small, but they add up over time. The average female lawmaker served five terms in office. That means working mothers sponsor five more child-related bills over their average tenure in Congress, compared with other women.

The differences are even starker if we consider the ages of lawmakers’ children. Women with children younger than 18 are more likely to write and introduce children and family measures than women with adult children or women without children. Working mothers with younger children sponsor over nine child-related bills each year, while “empty nesters” sponsor eight such bills and women without children only seven.

2. Working mothers often shepherd major family-focused measures into law

Working mothers in Congress have sponsored and helped to enact significant measures into law over the past several decades. Democratic Rep. Pat Schroeder, who represented Colorado from 1973-1997 and co-founded the Congressional Women’s Caucus, fought for nine years to secure passage of the Family and Medical Leave Act of 1993, considered one of her greatest legislative successes. In 2014, Rep. Jaime Herrera Beutler (R-Wash.) spearheaded a measure that allowed children on Medicaid facing complex medical procedures to receive treatment out of state, a measure she pursued after the birth of her daughter, who required out-of-state treatment for a rare condition. The bill passed the House in December and awaits approval by the Senate.

3. Expect more mom-led activism in the new Congress

In the 116th Congress, we expect legislative moms to continue championing bills affecting children and families, as with Gillibrand and DeLauro’s paid-family-leave bill. We may also expect to see mothers in Congress introduce and advocate for a number of education bills on issues ranging from increased access to early-childhood education and full-day kindergarten to more affordable higher education. Other issues that mothers may advance include increased access to breast-feeding for working mothers, tax credits for eldercare and affordable housing for families.

The majority of mothers in Congress are Democrats. Beyond the policies listed here, they are also likely to be some of the biggest supporters of legislation aimed at some other issues. Those include reducing gun violence and gun deaths, the issue that compelled new member Rep. Lucy McBath (D-Ga.) to seek office and campaign on after her son was shot and killed; ending family separations at the border; and expanding LGBTQ rights, including protections for same-sex parental rights and adoptions.

Julia Marin Hellwege is an assistant professor of political science at the University of South Dakota.

Lisa A. Bryant is an assistant professor of political science at California State University at Fresno.