As the U.S. birth rate reaches historic lows in 2025, these declines fuel economic change as the year comes to an end.
A University of Michigan study showed that low U.S. fertility has led to gains in pay equity. Eight percent of the narrowing gender pay gap came from women having fewer children.
The findings arrive amid a growing pronatalist push from policymakers and public figures urging the country to reverse its fertility decline.
"Increasing birth rates will tend to widen the pay gap, unless we find ways to reduce the motherhood wage penalty," said Alexandra (Sasha) Killewald, research professor at the Institute for Social Research.
Why did this decline happen?
By delaying or forgoing children, women secured continuous, high-skill employment, a structural shift with massive economic implications for future generations.
"The U.S. has made progress toward equal pay for men and women: in the mid-1980s, women only made 65% as much as men for every hour of paid work. Today, it's about 85%," sociologist Killewald said. "On the other hand, we still haven't reached pay equality for men and women."
Having kids affects men's and women's earnings differently, according to a study published in Social Forces and partly supported by the National Institutes of Health. Typically, when women become mothers, their wages drop-especially with each additional child. For men, becoming fathers actually boosts their earnings.
"When we think about the gender pay gap, we often think about how men and women differ in the characteristics employers care about, such as their education, field of study, work experience, occupation, and so on. And those factors are all important," Killewald said. "But our findings remind us that the work-related characteristics don't occur in a vacuum: the way men and women experience parenthood and women's greater responsibility for caregiving shape their work lives, affecting their wages."
The study looked at a large national dataset on American workers' family sizes and earnings over time. They found that in the 1980s, working Americans had on average 2.4 kids; by 2000, this dropped to 1.8-the most recent year in their analysis-and it's been steady since. As family sizes shrank, the gender pay gap became smaller.
It also found that motherhood is associated with wage losses for women in large part because mothers often take time out of the labor force or work part-time rather than full-time.
"Public investments in high-quality, affordable child care could allow more mothers to work for pay or to work more hours, if they want to," Killewald said. "It's also important to think about policies that would help dads share caregiving more equally with moms. In the U.S., long work hours are standard, making it hard for couples to maintain two careers while raising children. Policies that limit mandatory overtime or reduce the standard work week could help."
There are multiple goals in considering family policies, according to the author.
"We want individuals to be able to have the number of children they want on the timeline they want, to support their children financially and to have time to care for them," Killewald said. "We want men and women to have equal opportunities to work and parent in the ways they prefer. So, we may support policies that advance some of these goals, even if they don't advance others."
