Many fields that are traditionally dominated by women are set to expand in coming decades, while many jobs currently dominated by men are not. That’s the result of new research published Wednesday by Jed Kolko, an economist at job search site Indeed, which shows that less-educated men may especially face challenges in the job market of the future.

Jobs in the United States are still strongly divided by gender. A little more than one-third of men and a little less than one-third of women work in fields that are at least 80 percent staffed by their gender, according to U.S. Census data analyzed by Kolko.

In recent decades, fields that are dominated by men and by women have not fared equally. Many men have fallen out of work as increasing mechanization has allowed the U.S. to produce more agricultural and manufacturing goods than ever with fewer people than before.

Meanwhile, the U.S. economy has shifted more to service-sector jobs that are resilient to automation and tend to be more dominated by women – like healthcare, one of the sectors that is forecast to grow most in coming decades.

Jobs that are dominated by women are projected to grow nearly twice as fast as jobs that are dominated by men, Kolko says, citing data from the Bureau of Labor Statistics.

This dynamic is especially hurting less-educated men. As Kolko points out, the least-educated men in the United States tend to work in the most male-dominated jobs, with about half of all men with a high school degree or less working in fields that are at least 80 percent male.

In contrast, only slightly more than 10 percent of men with a graduate or professional degree work in fields that are 80 percent male. “Therefore, fast-growing male jobs that require lots of education don’t really help men without a college degree who have been in traditionally male jobs,” Kolko writes.

Fascinatingly, the trend isn’t the same for women. Women in the middle of the education spectrum — those with some college or an associate’s degree — are the most likely to work in more female occupations. But both women with the least education (those with no more than a high school degree or with no high school degree) and those with the most (those with a bachelor’s degree or with a graduate or professional degree) are less likely to work in female-dominated fields.

Of course, the gender identity of a job can change quite quickly, as history shows. Women once dominated computer programming, for example, a field which is now heavily male.

The jobs that President Donald Trump campaigned on bringing back to the United States — those of coal miners, steelworkers and farmers — are all traditionally male industries that have shrunk in recent decades. The White House has pledged to revive these industries, in part by encouraging manufacturing and penalizing companies that decide to move jobs offshore.

However, many economists say that bringing back once-high-paying jobs for less educated men will be difficult, if not impossible.

While federal policies could help to give farmers and manufacturers in the U.S. an edge over competitors and save some jobs on the margin, the sharp decline in agriculture and industrial employment is due to bigger structural shifts in the economy, like automation and globalization. Indeed, the percent of the population employed in manufacturing has fallen in advanced economies around the world in past decades.

Kolko points out that automation has also put some traditionally female jobs at risk. Telephone operators, textile workers and travel agents are all female-dominated fields that are set to shrink in coming decades.

Yet we don’t often hear the same nostalgia for the disappearance of these jobs as we do for manufacturing work. Part of the reason is likely economic, but part also seems tied up in ideas about masculinity and gender roles, as manufacturing jobs allowed less educated men to earn enough to serve as breadwinners for an entire family.

As economist David Autor pointed out to me in a recent conversation, few Americans are shedding tears for the loss of secretarial jobs in the United States, yet that field has disappeared for women, just as surely as factory work has declined for men. The difference is that many less educated men have struggled to find good jobs to replace it, while many women have generally moved to expanding and more lucrative fields, he said.

“We know in general as the labor market has become more skill intensive, women have educated themselves and adapted by moving quickly into other jobs,” Autor told me. “Women have moved on and up.”

There are a few traditionally male jobs that are set to grow in coming decades, including ambulance drivers, emergency medical technicians, personal finance advisers, web developers, computer scientists and actuaries, according to Kolko’s research.

But given the broader trends in the U.S. economy away from manufacturing and toward services, other American men may need to move into traditionally female roles in coming years if they want to thrive.