• Women in their 30s and 40s make up about 46% of total employment, slightly lower than those in their early 20s, according to an analysis by the Federal Reserve.
• Despite making major strides in the workplace, as women approach their 40s, caretaking responsibilities continue to drag down labor force participation.

Women in their mid-30s to mid-40s make up about 46% of total employment, which means they are slightly less likely to work than men that age, according to a recent analysis by the Federal Reserve. Their employment rate is also slightly lower than women in their early 20s.

"This smaller share reflects the fact that, within marriages, mothers are still more likely than fathers to specialize in child care," the Fed noted.

Despite making major strides in the workplace, as women approach their 40s, they are still more likely to take time out of the labor force or reduce the number of hours worked because of caretaking responsibilities, according to the Pew Research Center.

This also results in fewer opportunities for advancement and lower pay — often referred to as the "motherhood penalty."

Women are achieving increasing levels of education and working as much, if not more, than their male counterparts, at least until they reach an age when they often get married or have children — a dynamic that has proved remarkably stubborn.

"Women are more likely to exit the labor force either permanently or for a couple of years to take care of children," Kelly Shue, a professor of finance at Yale School of Management, said at CNBC's Women & Wealth event in September.

Today, 26% of mothers are stay-at-home parents, compared with just 7% of fathers, according to a separate Pew study from August.

Mothers working full time and year-round outside the home rarely recoup the lost wages, which add up to $20,000 a year, on average. Working moms are making just 71 cents for every dollar paid to fathers, according to an analysis of Census data by the National Women's Law Center. 

And they still shoulder the brunt of the responsibilities at home, many studies also show.

Even in cases where women are now breadwinners, the division of labor at home has barely budged, according to another 2023 Pew Research Center survey. 

As women's financial contributions increased, they continued to pick up a heavier load when it comes to household chores and caregiving responsibilities, the Pew report found.

"It is the case today, regardless of how much a woman is contributing economically, she is doing more tasks around the home," said Richard Fry, a senior researcher at Pew.

In fact, in some cases, their responsibility for child care and domestic tasks is only increasing.

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Four in 10 women with partners say they are responsible for most or all of the household work, a number that has grown since 2016, according to the annual Women in the Workplace study from Lean In and McKinsey.

This year, half of women who live with a partner and have children at home bear the most responsibility for child care — up from 46% last year, Deloitte's most recent Women at Work report also found.

At the same time, 37% of women said they feel like they have to prioritize their partner's career over their own — another increase from 2023 — in part because their partner earns more but also due to societal or cultural expectations.

However, in at least some marriages or partnerships, couples are reevaluating ideas about work and family and striking a balance between the two.

Recently, it's actually men who are choosing to scale back at work, particularly high earners with higher levels of education, according to a 2023 working paper published by the National Bureau of Economic Research.

"The pandemic may have motivated people to re-evaluate their life priorities and also gotten them accustomed to more flexible work arrangements (e.g., work from home), leading them to choose to work fewer hours, especially if they can afford it," the researchers wrote.