(The Conversation) – In 2024, women in the U.S. earned 85% of what men earned for each hour worked. This marks significant progress compared to the situation 40 years ago, where women earned only 65% of men’s hourly wages during the mid-1980s.

Advancements in women’s education, work experience, and transitions into higher-paying jobs have contributed to the rise in women’s earnings. Despite these improvements, the journey towards achieving pay equality has encountered stagnation.

As sociologists and demographers, we explored whether shifts within American families impacted women’s movement towards pay equity with men. Our article, published in Social Forces in June 2025, highlights a decreasing pay gap partly resulting from women having fewer children.

Moms earn less but dads earn more

In the U.S. and elsewhere, ample evidence shows that parenthood affects men’s and women’s wages differently.

Compared to remaining childless, motherhood leads to wage losses for women. And those losses are larger when women have more kids.

By contrast, after men become fathers their wages usually rise.

Because having kids tends to push women’s wages down and men’s wages up, parenthood widens the gender pay gap.

Decline in birth rate plays a role

The trend of fewer children is noticeable across the U.S. By around age 40, women, including those not employed outside the home, had an average of three children in 1980. This average dropped to 1.9 by 2000 and has remained relatively stable since.

We examined data from a nationally representative sample of U.S. families to understand if the number of children impacts earning disparities between working mothers and men. Specifically, we focused on trends regarding the number of children among employed Americans aged 30-55.

Our analysis revealed a decline in the average number of children employees had, decreasing from about 2.4 in 1980 to 1.8 by 2000. After 2000, this average held steady, with employees having approximately 1.8 children in the most recent year analyzed, 2018.

At the same time, the pay that women in this age range earned per hour relative to men rose steeply. It climbed from 58% in 1980 to 69% by 1990 and then rose more gradually to 76% by 2018. That is, as people were having fewer kids, the gender pay gap got smaller. For both trends, there was rapid change in the 1980s, followed by slower change after 1990.

We next estimated whether declines in the number of children men and women have can explain the narrowing of the gender pay gap between 1980 and 2018.

We found that, even after adjusting for other factors, such as years of education, prior work experience and occupation, about 8% of the decline in the gender pay gap can be explained by the lower number of children working women and men are having.

Next, we showed that the number of children American employees had declined faster in the 1980s than later on. That slowdown coincided with a deceleration of women’s gains in pay relative to men. Once the average number of children that U.S. employees had stabilized around 2000, so did women’s progress toward earning as much as men.

Questions about the future of US fertility

U.S. scholars and policymakers are debating whether and why Americans are having fewer children today than one or two decades ago, and what the government should do about it.

We agree that these are important questions.

Our research shows that any future changes in how many children Americans have are very likely to affect how quickly women and men reach pay equality. But it’s not inevitable.

The number of children Americans have affects the gender pay gap only because parenthood decreases women’s wages while increasing men’s wages. As long as these unequal effects of parenthood on what men and women earn persist, they will continue to act as a brake on women’s progress toward equal pay.