Less than one in five third-graders from low-income families score at or above the national average in math, reading and science assessments, and only about half maintain a healthy weight and are in "excellent" or "very good" health.
That compares with about half of children from higher-income families who are scoring above average on standardized tests and 62 percent of children from wealthier families who are in very good health.
Such disparities in early achievement and health are illustrated in a report by the Annie E. Casey Foundation called "The First Eight Years: Giving Kids a Foundation for Lifetime Success." The report, which is being released Monday, tracks children’s well-being across multiple areas and in every state.
The report argues that for all children to have a strong foundation, they need better access to quality early care and education, and coordinated health care and support services for their families.
Policy recommendations include stronger parental leave policies, mental-health services for new mothers and broader access to quality, affordable day care and preschool.
"All children need nurturing and plentiful opportunities to develop during their crucial first eight years," said Patrick McCarthy, president and chief executive of the foundation.
"Today’s complicated world can strain families’ ability to ensure their children are receiving all the stimulation and care they need to develop to their full potential," he said.
The report shows that children from low-income families are less likely to perform well in social and emotional skills, such as exhibiting self-control (63 percent compared with 75 percent of children from wealthier families) and are less likely to show interest and participate in learning activities (66 percent compared with 80 percent).
The study draws on data from the government-funded Early Childhood Longitudinal Study, which tracks children over time.
Nearly half of children 8 years old and younger are living in low-income households, according to the report. The poverty marker is defined as those with incomes below 200 percent of the 2012 federal poverty threshold, or $46,566 for a family of two adults and two children.
That includes 42 percent of children in the District, 34 percent of those in Maryland and 38 percent in Virginia.
Mississippi has the highest proportion of children 8 and younger considered low-income — 63 percent.