Becoming a parent can be life-transforming, and some parents choose to leave the workforce temporarily to spend more time with young children. (And for mothers, taking at least some time off is unavoidable.) However, a new survey suggests that most parents who take a hiatus from work end up staying out of the labor market longer than they expected.

Employment search company FlexJobs asked more than 900 stay-at-home parents who were thinking of going back to work about their decision to take time off and their plans to re-enter the workforce. A majority of those surveyed (58%) said they ended up being out of work longer than initially planned, and 39% said they took “a lot more time” off from their career than they had intended.

Only 6% reported returning to work sooner than expected.

While most of the stay-at-home parents (65%) went on leave because they wanted to spend time with their children, some paused their jobs for additional reasons:

• 36% wanted to keep working but said their jobs were too inflexible for a working parent

• 25% couldn’t find affordable or quality child care

• 21% took time off because their partner’s salary was higher

• 13% had been laid off

• 12% had children with special needs who require more care

Parents also varied on how much time they initially expected to be away from their careers. Of the respondents, 27% weren’t sure how long they’d ultimately take off, but others had more concrete plans: 23% expected to take off 1-2 years, 14% planned to be home for 2-5 years, and 14% anticipated being out of the workforce for more than 5 years.

Regardless of the reason for taking time away from their jobs, the move was likely to affect the parents in terms of both family finances and career trajectories.

To contribute to the household income while they were out of work, 34% said they freelanced or did gig work, 11% participated in multi-level marketing opportunities, 7% provided childcare for other parents, and 5% made and sold crafts.

More than a third of parents surveyed (34%) said they had left management-level or senior-management-level jobs. Another 55% described their career levels as “experienced,” and 9% said they left entry-level jobs.

When it came to going back to work, money was the biggest motivator, with 85% saying they wanted to earn income for their families, and 56% saying their families needed the extra money.

Yet 88% reported some concerns about what their experience would be when they got back to work. An overwhelming majority—73%—worried that they would have to take a pay cut when they returned, and 50% expected to start at a lower level than when they left.

While many parents would likely describe spending time with children as invaluable, there is a real cost to leaving the workforce that families can prepare for. If you intend to take time off to take care of your child (or for any other reason), not only will you lose the steady paycheck, but you might lower your earning potential for the rest of your professional career.

Families can prepare for that by saving as much as possible when both parents are working and by cutting down on expenses so that the family budget can go further. Stay-at-home parents can also look for remote opportunities and gig work that can allow them to make money while taking care of their children at home.