The Future of Children, Princeton - Brookings: Providing research and analysis to promote effective policies and programs for children.

The research reviewed thus far suggests that living in poverty exacts a heavy toll on children. However, it does not shed light on the pathways or mechanisms by which low income exerts its effects on children. As the term is used in this discussion, a "pathway" is a mechanism through which poverty or income can influence a child outcome. By implication, this definition implies that a pathway should be causally related to both income and at least one child outcome. Exploration of these pathways is important for a more complete understanding of the effects of poverty on children; moreover, exploration of pathways can lead to the identification of leverage points that may be amenable to policy intervention and remediation in the absence of a change in family income.

Research on the size and strength of the pathways through which income might influence child health and development is still scanty. In this section, five potential pathways are discussed: (1) health and nutrition, (2) the home environment, (3) parental interactions with children, (4) parental mental health, and (5) neighborhood conditions. Space limitations preclude a discussion of other potential pathways such as access to and use of prenatal care, access to pediatric care, exposure to environmental toxins, household stability, provision of learning experiences outside the home, quality of school attended, and peer groups. Further, few studies have tested pathway models using these variables.

Although health is itself an outcome, it can also be viewed as a pathway by which poverty influences other child outcomes, such as cognitive ability and school achievement. As discussed previously, poor children experience increased rates of low birth weight and elevated blood lead levels when compared with nonpoor children. These conditions have, in turn, been associated with reduced IQ and other measures of cognitive functioning in young children and, in the case of low birth weight, with increased rates of learning disabilities, grade retention, and school dropout in older children and youths.

A 1990 analysis indicated that the poverty-related heath factors such as low birth weight, elevated blood lead levels, anemia,³⁸ and recurrent ear infections and hearing loss contributed to the differential in IQ scores between poor and nonpoor four-year-olds.³⁹ The findings suggest that the cumulative health disadvantage experienced by poor children on these four health measures may have accounted for as much as 13% to 20% of the difference in IQ between the poor and nonpoor four-year-olds during the 1970s and 1980s.³⁹

As discussed in the Child Indicators article in this journal issue, malnutrition in childhood (as measured by anthropometric indicators) is associated with lower scores on tests of cognitive development. Deficits in these anthropometric measures are associated with poverty among children in the United States, and the effects can be substantial. One recent study found that the effect of stunting on short-term memory was equivalent to the difference in short-term memory between children in families that had experienced poverty for 13 years and children in families with incomes at least three times the poverty level.²⁶

A number of studies have found that a child's home environment—opportunities for learning, warmth of mother-child interactions, and the physical condition of the home—account for a substantial portion of the effects of family income on cognitive outcomes in young children. Some large longitudinal data sets use the HOME scale as a measure of the home environment. The HOME scale is made up of items that measure household resources, such as reading materials and toys, and parental practices, such as discipline methods. The HOME scale has been shown to be correlated with family income and poverty, with higher levels of income associated with improved home environments as measured by the scale.^7,40

Several studies have found that differences in the home environment of higher and lower-income children, as measured by the HOME scale, account for a substantial portion of the effect of income on the cognitive development of preschool children and on the achievement scores of elementary school children.^6,26,37 In one study, differences in the home environment also seemed to account for some of the effects of poverty status on behavioral problems. In addition, the provisions of learning experiences in the home (measured by specific subscales of the HOME scale) have been shown to account for up to half of the effect of poverty status on the IQ scores of five-year-olds.^37,41

A number of studies have attempted to go beyond documentation of activities and materials in the home to capture the effects of parent-child interactions on child outcomes. Much of the work is based on small and/or community-based samples. That work suggests that child adjustment and achievement are facilitated by certain parental practices. There is also some evidence that poverty is linked to lower-quality parent-child interaction and to increased use of harsh punishment. This research suggests that parental practices may be an important pathway between economic resources and child outcomes.

Evidence of such a parental-practice pathway from research using large national data sets of the kind reviewed in this article is less consistent. One NLSY-based study found that currently poor mothers spanked their children more often than nonpoor mothers and that this harsh behavior was an important component of the effect of poverty on children's mental health.³² Mothers' parenting behavior was not, however, found to be an important pathway by which persistent poverty affected children's mental health. A more recent study using the National Survey of Families and Households found that the level of household income was only weakly related to effective parenting and that differences in parent practices did not account for much of the association between poverty and child well-being.⁴²

Among adolescents, family economic pressure may lead to conflict with parents, resulting in lower school grades, reduced emotional health, and impaired social relationships.^33,43 Other work suggests that it may be income loss or economic uncertainty due to unemployment, underemployment, and unstable work conditions, rather than poverty or low income per se, that is a source for conflict between parents and teens leading to emotional and school problems.^33,44

Parents who are poor are likely to be less healthy, both emotionally and physically, than those who are not poor.⁴⁵ And parental irritability and depressive symptoms are associated with more conflictual interactions with adolescents, leading to less satisfactory emotional, social, and cognitive development.^43,46,47 Some studies have established that parental mental health accounts for some of the effect of economic circumstances on child health and behavior. Additionally, poor parental mental health is associated with impaired parent-child interactions and less provision of learning experiences in the home.^33,41,48

Another possible pathway through which family income operates has to do with the neighborhoods in which poor families reside. Poor parents are constrained in their choice of neighborhoods and schools. Low income may lead to residence in extremely poor neighborhoods characterized by social disorganization (crime, many unemployed adults, neighbors not monitoring the behavior of adolescents) and few resources for child development (playgrounds, child care, health care facilities, parks, after-school programs).^49,50 The affluence of neighborhoods is associated with child and adolescent outcomes (intelligence test scores at ages 3 and 5 and high school graduation rates by age 20) over and above family poverty.^37,51 Neighborhood residence also seems to be associated with parenting practices, over and above family income and education.⁵² Neighborhood effects on intelligence scores are in part mediated by the learning environment in the home.^52,53 Living in neighborhoods with high concentrations of poor people is associated with less provision of learning experiences in the homes of preschoolers, over and above the links seen between family income and learning experiences.

A key issue that has not been fully explored is the extent to which neighborhood effects may be overestimated because neighborhood characteristics also reflect the choices of neighborhood residents. One study that examined the effects of peer groups (as measured by the socioeconomic status of students in a respondent's school) on teenage pregnancy and school dropout behavior found that while student body socioeconomic status seemed to be an important predictor of both dropout and teen pregnancy rates, it did not appear to be related to those outcomes in statistical models that treated this peer characteristic as a matter of family choice.⁵⁴