Child care is expensive — second only to the mortgage or rent in the average family budget. Infant care is more expensive than in-state public college tuition in 31 states. And costs to parents have nearly doubled in the last 25 years.

Yet in those same 25 years, as the share of children in some kind of child care setting has grown to 75 percent of those under age 5, child-care teachers and staff have seen no real increase in their earnings, according to a report released Tuesday by the Center for the Study of Child Care Employment at the University of California, Berkeley.

Nearly half of all child-care workers are so poor that they qualify for public assistance like food stamps, Medicaid and the Earned Income Tax Credit, according to the report, “Worthy Work, STILL Unliveable Wages,” an update of a 1989 national child care staff study.

More than half of all child-care teachers are single. And of the parents, more than half are single parents, the report found.

“We pay our child-care workers on par with the people who park our cars, walk our dogs and flip our hamburgers. Is that really what we want for the people who are teaching our young children and getting them ready for school?” said Deborah Phillips, a psychology professor at Georgetown University and one of the report authors in both 1989 and 2014. “There is such a disparity between what parents pay and what teachers earn. Even having studied this for the past 25 years, it’s still shocking to me.”

Of the more than 600 teachers and staff members whom Phillips and her co-authors surveyed, three-fourths worried about having enough money to pay their monthly bills. Nearly half felt anxious about having enough food for their families. Poorly paid teachers and staff, the report notes, have led to higher teacher turnover rates, less continuity, and more instability and chaos for children.

Phillips said she and her co-authors wanted to revisit their 1989 report because of the wealth of neuroscientific research that has since emerged about how critical a child’s first five years are in developing the architecture of their brains – how positive engagement and attachment with caring adults can lead to future health and academic achievement, and how toxic stress can alter a child’s genetic blueprint and impair memory, learning, emotion control and physical and mental health.

“Our nation has never really come to terms with the fact that early education really is rocket science,” Phillips said. “We’re still straddling this fundamental divide between thinking about what happens before kindergarten as babysitting, rather than thinking of it as the best investment we could possibly make in a child’s development.”

Economists and several longitudinal studies have found a long-term rate of return of $3 to $7 for every dollar spent on high-quality early childhood education, in greater academic success, better jobs and reduced rates of incarceration and reliance on public assistance.

Meeghan Bergmann, 23, has a bachelor’s degree in social work but earns $13.37 an hour as a child-care worker in Seattle. With her salary, she could qualify for public housing and other public benefits, but because her husband is from Uganda and has only a green card, they are barred from receiving the assistance.

“We pretty much live paycheck to paycheck,” Bergmann said. Teachers at her nonprofit child-care center haven’t had raises in five years, while at the same time rents in the city have increased 11 percent, the steepest jump in the country, according to the U.S. Census. Some child-care workers live in the same subsidized housing where their low-income students’ families live.

And the pay is so low that child-care teachers and staff don’t last long. Though Bergmann has worked for about a year at the center, so many teachers have left that she is now one of the most senior on the staff of 24.

“A lot of our kids have chaotic lives. The idea is that they’ll develop relationships with teachers here and feel secure so they can develop normally,” Bergmann said. “But the high turnover rate is disruptive. One boy lost his teacher, and it affected him so much he couldn’t function. He trusted someone, and then they were gone.”

Bergmann, who is applying to graduate school, once considered coming back to the center to work as a counselor. But after having to live on such low wages, she has changed her mind.

Tonia McMillian, a family child-care provider in Los Angeles and co-chair of Raise Up California, is trying to organize child-care workers to push for better wages and fair reimbursement rates for providers who accept low-income children with subsidized vouchers. Right now, the state hasn’t raised reimbursement rates since 2004.

“You get into this business because you’re passionate about kids,” she said. “ I don’t know anyone who gets in because they want to be rich. Still, I worry about finances all the time.”

In the report, Phillips said that while child-care workers’ salaries increased barely 1 percent in the last 25 years, preschool teachers fared somewhat better: Their salaries increased 15 percent as more states embraced universal pre-K programs as part of their education systems. Still, preschool teachers earn about 60 percent of the hourly wage of kindergarten teachers.

Despite the increased costs to parents, national studies of the quality of child care have found that it’s uneven at best – with a handful of excellent, expensive, high-quality programs, a majority of mediocre programs and a handful that have actually proven dangerous to children. State standards are all over the map.

The U.S. Senate passed a bipartisan bill Monday to reauthorize the Child Care and Development Block Grant for the first time since 1996 that would also, for the first time, set federal standards for health, safety and quality. For instance, child-care providers who receive federal child-care subsidies for low-income children must now know CPR and healthy sleeping practices to avoid sudden infant death syndrome. And all providers will for the first time go through a mandatory background check.

The bill, which has already passed the House, now moves to President Obama for action. But those new health and safety requirements will only apply to the child-care providers who accept low-income children who receive federal subsidies.

The report released Tuesday calls for a thorough assessment of the nation’s entire early education system and policy: public, private, for profit and nonprofit. “One of the first steps we’re going to have to deal with, is simply how we finance the early care system. The money cannot keep coming from the pockets of the parents,” Phillips said. “It’s just not there. And it’s not fair.”

Although child-care teachers and staff in many other advanced economies are paid on par with public school teachers, and costs are subsidized in part by the government, Phillips pointed to a successful model closer to home: the Department of Defense.

The Defense Department employs 22,000 early childhood education teachers and staff who care for 200,000 children, many in high-quality centers accredited by the National Association for the Education of Young Children. After a massive reform in 1989, early childhood education teachers are now paid at the same rate as other civilian employees, based on experience. Teachers receive training. And DOD subsidies cover about two-thirds of the cost of care, based on a sliding scale according to income.

Staff turnover rates have fallen from a high of 300 percent to an average of 27 percent, according to the report.

“The U.S. Department of Defense has figured out how to break the zero-sum equation between parent fees and teacher salaries,” Phillips said. “Other countries have figured it out. There are answers. We’ve just been stuck for so long. It’s time we looked at all possibilities.”