By not adapting to the needs of working parents, U.S. employers might be losing as much as $300 billion a year in lost productivity, new research shows.

In a survey of 1,755 working parents nationwide, one in 20 said they were severely impacted by concerns about after-school childcare, according to researchers at Brandeis University and Catalyst, a New York-based non-profit research firm.

There are about 53 million parents in today's workforce, Labor Department figures show.

The level of stress they feel at work can manifest itself in everything from minor workplace disruptions  to lower job satisfaction, and can be "very toxic to employee attitudes, work performance, and well-being," said Karen Gareis, a social psychologist who led the study.

The study found parents who work longer hours, have greater responsibility for childcare at home, or whose children spend more unsupervised time risk the highest stress levels.

Since older children were more likely to spend unsupervised time after school, parents tended to worry more about them and less about children in kindergarten though grade 5, the study found. Though working mothers were slightly more prone to worry about their children, workplace stress generally cuts across gender, racial, and ethnic lines, the study found.

Stress over after-school care is an "equal-opportunity issue," Ilene Lang, the president of Catalyst, said in a statement.

By contrast, parents with low stress levels  were those who felt they had more control over their work schedules, or have a partner whose work schedule allowed them to be home after school, the study found.

"Businesses can increase productivity and retention in today's round-the-clock work environment by cultivating an agile, results-focused workplace, where work and life responsibilities aren't mutually exclusive," Lang said, calling it a "win-win" situation for employers and workers alike.

The study recommends employers put greater emphasis on "job control" by giving all employees more flexible schedules, including creating opportunities for flex-time, telecommuting, and flex-space.

More than 75 percent of respondents said greater flexibility to arrive at work later or leave earlier, or take half-days when necessary, significantly cuts down on stress.

More generally, the study calls for expanding support for after-school care and community services, educating supervisors and managers about the needs of working parents, and better communicating existing workplace support policies and programs.

These can include everything from subsidies for after-school care, to volunteer leave and bankable hours, researchers said.