In 2010, more than one in five children (22 percent) lived in families with incomes below the poverty line, the highest level since 1993; by 2014, this had fallen to 21 percent. Black and Hispanic children, children living in single-mother families, and children under five are even more likely to be poor.
Since the mid-1970s, children under 18 have been much more likely than adults to be poor. Being raised in poverty (defined as income of $24,008 or less in 2014, for a family of four with two children)  places children at higher risk for a wide range of problems. Research indicates that poor children are disproportionately exposed to factors that may impair brain development  and affect cognitive, social, and emotional functioning. These risks include environmental toxins, inadequate nutrition, maternal depression, parental substance abuse, trauma and abuse, violent crime, divorce, low-quality child care, and decreased cognitive stimulation (stemming in part from exposure, in infancy, to a more restricted vocabulary,,
While determining causality is complex in this context, experiencing poverty is also related to increased risks of negative health outcomes for young children and adolescents. When compared with all children, poor children are more likely to have poor health and chronic health conditions. Children in poor families are more likely to be born premature and at a low birth weight, and to develop later illnesses, such as respiratory diseases. As adolescents, poor youth are more likely to suffer from mental health problems, such as personality disorders and depression. Moreover, in comparison to all adolescents, those raised in poverty engage in higher rates of risky health-related behaviors, including smoking and early initiation of sexual activity.,,
Aside from physical and mental health, poverty in childhood and adolescence is associated with a higher risk for poorer cognitive and academic outcomes, lower school attendance, lower reading and math test scores, increased distractibility, and higher rates of grade failure and early high school dropout., Poor children are also more likely than other children to have externalizing and other behavior problems, or emotional problems,, and are more likely to engage in delinquent behaviors during adolescence. Finally, growing up in poverty is associated with lower occupational status and lower wages,, poorer health, and deficits in working memory in adulthood.
Reporting on child poverty rates at a single point in time gives an under-estimate of its deleterious effects, since research shows that persistent poverty, as well as poverty experienced in the childhood’s early years, is most detrimental to development. Nearly four in ten children are poor for one or more years before they reach age 18—nearly double the point-in-time estimate. More than one in ten are poor for half or more of their childhood years.
Source: Child Trends