(Reuters Health) - Almost half of women and a quarter of men leave careers in science, technology, engineering and math after they have their first child, a new study shows.

Researchers found that 43 percent of women and 23 percent of men walk away from full-time STEM jobs after starting a family, according to the study released by the Proceedings of the National Academy of Sciences of the United States of America.

The new research may provide at least a partial explanation for both the gender gap in the STEM fields and the shortage of STEM professionals in the U.S.

“What’s so striking about our results is that the ones with the education who already have STEM jobs are the ones who are leaving,” said Erin Cech, an assistant professor in the department of sociology at the University of Michigan. “If we want to build up a STEM workforce, we should be keeping the ones who are there already. They are the ‘low hanging fruit.’”

To take a look at the possible impact of parenthood on STEM jobs, Cech and her coauthor, Mary Blair-Loy, a professor of sociology at the University of California, San Diego, analyzed data from a large survey of STEM professionals conducted between 2003 and 2010 by the National Science Foundation.

The researchers looked only at full-time STEM professionals who did not have children at the time they filled out their first questionnaires for the nationally representative survey, known as SESTAT (Scientists and Engineering Statistical Data System).

While 11 percent of the moms switched to part-time low paying STEM jobs after having or adopting a first child, another 15 percent dropped out of the workforce entirely, Cech said. Many opted to switch careers, presumably finding that jobs in areas such as management, marketing, and the service industry were more compatible with family life, she added.

For some, the issue may be the absence of paid family leave, Cech said. “The United States has some of the worst parental leave policies in the industrialized world,” she added.

Cech has some math advice for companies that feel they can’t afford to pay for parental leave.

“Some organizations argue that they don’t want to pay for better paid leave policies,” she said. “But the cost of turnovers of STEM professionals is higher. The cost of finding replacements and training them for such highly skilled jobs can often turn out to be as much as one to one and a half times the year’s salary for that position - substantially more than giving them two months of paid leave.”

The new findings are important, said Dr. Albert Wu, an internist and professor of health policy and management at the Johns Hopkins Bloomberg School of Public Health.

“It’s evident we are losing many valued and highly trained contributors to the workforce in science, technology, engineering and math at a time when there are indications that we are becoming less competitive on the world’s stage,” said Wu, who was not involved with the new research. “So this is an unfortunate and potentially preventable self-inflicted wound.”

The problem isn’t isolated to STEM careers, Wu said, but there “is still too much machismo in the attitudes of many leaders in these professions. They say, ‘it’s their choice. They’re making their own priorities. If this job is not their top priority maybe they’re just not cut out for this type of work.’”

But, Wu said, having children is a part of life. “We should not be encouraging people to avoid parenthood to work in STEM fields,” he added. “What we need to change is how we design our work.”

SOURCE: bit.ly/2TVhX3J Proceedings of the National Academy of Sciences USA, released February 18, 2019.