We live in a 24/7 working world, where smartphones and PCs act as digital leashes, making it harder than ever to strike a work/life balance. As a result, numerous companies are now instituting flexible work arrangements and paid time off, responding to numerous studies revealing that happy employees are more productive. Nevertheless, studies reveal that taking advantage of these perks could sabotage future wages, risk a promotion or — worse — chance a layoff.

This puts parents in a particularly tough spot: prioritizing time with the kids or focusing on the means of providing for them. Trying to balance kids while working or opting out of the workforce for a little while can have severe career implications in terms of hiring prospects and future wages, says Kate Weisshaar, an assistant professor in the department of sociology at the University of North Carolina at Chapel Hill. This is referred to as the "parenting penalty."

This issue extends to a variety of workers in a variety of situations: those who wish to leave the office early to see their kid's school play or attend a parent/teacher conference; new parents who desire an extended maternity/paternity leave; part-timers, attempting to sufficiently bridge their duties to both their families and their employers; and those who go so far as to leave the job market for a few years to focus on their children during their formulative years.

"In a lot of workplaces, there is an expectation from employers that employees devote themselves fully to work," said Weisshaar. "The expectation to work long hours, to be highly dedicated to work and to always be available can introduce challenges for parents, or any caregivers, who have other demands on their time besides work. So if employers are making promotion or hiring decisions based on these types of expectations and/or assumptions that parents can't or won't live up to expectations, then parents may be blocked from opportunities at work."

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Weisshaar says stay-at-home mothers and fathers face a huge disadvantage when trying to reenter the workforce — more so than job applicants that were employed and laid off. Parents who temporarily exit the workforce to spend time with their children are only half as likely to get a job interview than those who have been laid off, she said.

According to a recent study by Working Families, a U.K.-based charity that advocates for working parents, parents who work part-time have a 21% chance of being promoted within the next three years. Full-time counterparts have a 45% chance. And the average mother, the group says, waits two years longer for a promotion than the average father.

The study was focused on the U.K., says Catherine Gregory, head of marketing and communications for Working Families, but the results translate across borders.

"Eighty percent of parents we surveyed are working beyond their contracted hours," she says. "Part of that is poor job design, where employers are creating jobs that can't be completed in the time allocated. But it's also expected. Over half the people we spoke with said that's just part of their company culture. It's an expectation from their employer that they're supposed to be there and do extra work."

Although many companies are trying to promote a more family-friendly atmosphere, the U.S. still lags far behind the rest of the world when it comes to paid family leave. A 2016 Pew Study found that American workers were the only one of 41 countries that did not have a mandate for paid leave for parents. (Estonia, meanwhile, offers an astonishing 87 weeks.)

That not only affects parents of newborns but can cause problems as children get older and lead more active lives.