"More than 40 percent of all children live in low-income families — including 5.2 million infants and toddlers under 3," reports the National Center for Children in Poverty (NCCP) at Columbia University's Mailman School of Public Health.
These families are not poor because they are lazy. From EurekAlert:
The majority of children in low-income families have at least one parent who works full time, all year long. Children whose parents are employed full time are less likely to live below the poverty line, but earning a wage was no guarantee of economic security in 2015, according to NCCP research. More than half (53 percent) of low-income children and 31 percent of poor children live with at least one parent employed full time, throughout the year.