Most Americans say they have taken or are very likely to take family or medical leave at some point (62%), but many, particularly among lower-income workers, aren’t able to take time off from work when these situations arise, according to a new Pew Research Center study.

About one-in-six adults (16%) who have been employed in the past two years say there was a time during this period when they needed or wanted to take time off from work following the birth or adoption of their child, to care for a family member with a serious health condition or to deal with their own serious health condition, but were unable to do so. This figure rises to 30% among those with household incomes under $30,000.

Among workers who have faced this situation in the past two years, the most frequent reason (cited by 72%) for not taking family or medical leave when one needs or wants to is concern over loss of wages or salary. Just over half of workers (54%) say they feared losing their job, while about four-in-ten say they felt badly about their co-workers taking on additional work (42%) or worried that taking time off might hurt their chances for job advancement (40%). Other reasons cited include believing that no one else was capable of doing their job (36%) or their employer denying their request for time off (32%).

Across income groups, majorities of those who weren’t able to take time off worried about the potential loss of wages or salary. But those with lower incomes are considerably more likely than those with higher incomes to say their employer denied their request for time off or that they thought they might risk losing their job if they took time off.

For example, 65% of those with household incomes under $30,000 who didn’t take leave when they needed or wanted to say they thought they might risk losing their job if they took time off, compared with about half of middle- and higher-income workers.

And 42% of those with household incomes under $30,000 say their leave request was denied, compared with 32% of those with incomes between $30,000 and $74,999 and 24% of those with incomes of $75,000 or more.

Conversely, workers with household incomes of $75,000 or higher (45%) are more likely than those with lower incomes to say they didn’t take time off when they needed or wanted to because they felt no one else could do their job. Three-in-ten workers with incomes below $75,000 point to this as a reason.

While many workers who didn’t take family or medical leave say they had access to some benefits that might have allowed them to receive pay, relatively few among those with incomes under $30,000 say this was the case. For example, 29% of those with household incomes under $30,000 say they had paid vacation days, sick leave or personal time off (PTO) available to them at the time, compared with 49% of those with incomes between $30,000 and $74,999 and 60% of those with incomes of $75,000 or more.

Just 13% of those with incomes under $30,000 and 15% of those with incomes between $30,000 and $74,999 say they had access to employer-paid family or medical leave benefits separate from vacation, sick leave or PTO. By contrast, a quarter of those with incomes of $75,000 or more say the same.

Overall, about half (49%) of those who needed or wanted to take leave but were not able to do so say it was difficult for them to learn about what leave benefits, if any, were available to them at the time.

Many workers who didn’t take time off when they needed or wanted to say this experience had an adverse effect on their family. A plurality (45%) say that not taking time off had a negative impact on their family, while 21% say it had a positive impact and a third say it didn’t make much difference.