Rarely do poverty and optimal health go together. In fact, income is consistently tapped as a major factor underpinning a person’s opportunity to live a long and healthy life. And children don’t fare much better, with low-income children facing increased risks of poor health and development. So, just how many American children face this challenge today? Four out of every 10.

This month, researchers at the National Center for Children in Poverty at Columbia University Mailman School of Public Health released their annual “Basic Facts about Low-Income Children” fact sheet, which reports that 44 percent (31.8 million) of U.S. children younger than 18 lived in low-income families in 2013, and 22 percent (15.8 million) lived in families considered poor. (Low-income is defined as families with incomes less than two times the federal poverty threshold, or about $47,000 for a family of four; while poor families are defined as those with incomes below the threshold, or $24,000 for a family of four.) Those poverty numbers are far higher than they were before the Great Recession — in 2007, 39 percent of children were living in low-income families.

The fact sheet found that while the overall number of U.S. children increased by less than 1 percent between 2007 and 2013, the numbers of children living in low-income and poor families went up by 13 percent and 23 percent, respectively.

“Far too many American children live in economically insecure families, and this serious threat to our nation’s future does not get the attention it deserves,” said Renee Wilson-Simmons, the center’s director, in a news release.

Researchers, who based their findings on the latest data from the U.S. Census, also found that younger children are more likely to live in low-income and poor families than older children. For example, 5.8 million children ages 3 to 5 — or nearly half of the 3- to 5-year-old population — live in low-income families, compared to 41 percent of children ages 12 to 17. Black, Hispanic and American Indian children disproportionately live in low-income and poor households: 65 percent of black children live in low-income families, 63 percent of Hispanic children do, and 63 percent of American Indian children do. Comparatively, 31 percent, or 11.7 million, white children live in low-income families.

Noting that children who have parents with full-time, year-round employment are less likely to be low-income, the fact sheet reports that in 2013, 15.9 million children with at least one parent working full-time lived in low-income families. Nine percent, or 4.5 million, children with the same parental employment conditions lived in poor families. Among children with at least one parent who worked part-time or part of the year, 74 percent lived in low-income families and 48 percent lived in poor families. Also, living in a low-income family wasn’t confined to children whose parents had lower educational attainment: Forty-one percent of poor children in 2013 had at least one parent with some college education.

When it comes to health insurance coverage, low-income and poor older children are more likely to go uninsured than younger children. Researchers reported that in 2013, 10 percent of children in low-income families had no insurance, 27 percent of kids in low-income families had private health coverage and 68 percent of such children had public insurance. Geographically, the American South was home to the largest percentage of low-income children, followed by the West, Midwest and Northeast.

To download the entire fact sheet, visit the National Center for Children in Poverty.

Kim Krisberg is a freelance public health writer living in Austin, Texas, and has been writing about public health for more than a decade.