Journal Issue: School Readiness: Closing Racial and Ethnic Gaps Volume 15 Number 1 Spring 2005
The Importance of Maternal Health Conditions and Behaviors
In this section I focus on two aspects of maternal health conditions and behaviors that significantly affect children's cognitive and social functioning and that are also characterized by large racial disparities. Because many other maternal health behaviors could be considered, my purpose here is merely to illustrate how potentially important maternal behaviors can be.
The first behavior, breast feeding, exhibits large disparities by race. The American Academy of Pediatrics recommends that infants be breast fed exclusively for their first six months and that cow's milk not be introduced until after the first birthday. Some 70 percent of white infants, but only 40 percent of black infants, have ever been breast fed. At six months, 29 percent of white infants, but only 9 percent of black infants, are still being breast fed.28
Theoretically, breast feeding affects a child's cognitive development through three channels. First, it prevents diseases such as ear infections and may even prevent asthma. To the extent that poor physical health impairs children's performance, a lack of breast feeding could thus be implicated. Second, breast feeding provides nutrients, such as long-chain fatty acids that may affect infants' brain development, that are not adequately provided in most infant formula sold in the United States. Third, breast feeding may promote maternal-infant bonding that may, in turn, be beneficial for learning. Many studies link breast feeding positively with cognitive skills. Typically they find IQ gains of two to five points for healthy infants and up to eight points for low birth weight babies. Once again, however, given the strong relationship between breast feeding and various measures of socioeconomic status, it is unclear whether the association between breast feeding and cognition is causal.29
If, however, breast feeding does affect IQ scores, then the racial differences in prevalence are large enough to explain a significant part of the gap in the generic test score that I have been considering. Suppose, for example, that breast feeding for six months raises IQ by five points, or about one-third of a standard deviation. Then the fact that 29 percent of white infants, but only 9 percent of black infants, are breast fed for six months would generate a one point difference in average scores (with the assumed black-white gap being eight points).30
Although my emphasis in this article has been on child health, the mental health of the mother may be a key determinant of the health of the child. The difficulties associated with poverty or racism, or both, may leave some mothers more vulnerable to depression, and depressed mothers may be less able than healthy mothers to provide a stimulating and nurturing environment for their children. The hypothesis that differences in rates of maternal depression could be associated with group-level differences in the attainments of children, however, has not been directly tested, so it is necessary to go through each link in the causal chain.
Evidence abounds that poverty is associated with a higher risk of depression. The poor are 2.3 times more likely to be depressed than the nonpoor, adjusting for age, gender, ethnicity, and prior history of depression. This higher risk may be due both to heightened stress and to a lack of resources to cope with that stress. The incidence of pregnancy and postpartum depression in a sample of poor, inner-city women is about one-quarter, double the rate typically found among middleclass women. In the Infant Health and Development Study, 28 percent of poor mothers, as against 17 percent of nonpoor mothers, were depressed.31
Given that blacks are generally poorer than whites, one might expect a higher prevalence of depression among black mothers than among white mothers. But research findings are mixed. Some studies have shown higher rates of depressive symptoms among blacks than whites, but studies that use the diagnostic criteria for major depression generally find little racial difference in incidence. The National Comorbidity Study and Epidemiological Catchment Area Studies found that blacks were less likely than whites to be depressed, whereas another study found no racial difference in the incidence of depression in a sample of poor women. These findings suggest that although poor mothers may be at higher risk than others, race does not play an independent role in explaining the incidence of maternal depression. It is possible that both race and socioeconomic status affect whether, and how effectively, women are treated for depression, but there is little hard evidence that race, per se, is a factor.32
Studies of the relationship between maternal depression and child development can be divided into several groups. First, observational studies of the way depressed mothers interact with their infants find that they are often inconsistent and ineffective in disciplining their children, more likely to use force rather than compromise, and less likely to interact in a positive way. These problems are more apparent among impoverished mothers with depression than among their better-off counterparts. Second, many studies document a relationship between maternal depression and both current and future child behavior problems, insecure attachment, and cognitive problems. Maternal depression, they find, can reduce test scores by about a third of a standard deviation among preschool children.33
It is not clear that maternal depression causes these negative outcomes: the link between the two could also reflect shared genes or a shared response of the mother and child to other external causes. It is also unclear how pervasive or persistent child responses to maternal depression are. Several studies, for example, find the effects of postpartum depression confined to boys.34
With 37.5 percent of black children under five and 15.5 percent of white children in that same age group living in poverty, the socioeconomic gap in the incidence of maternal depression noted above—28 percent among the poor, 17 percent among the nonpoor— means that maternal depression will affect some 11 percent of black preschool children but only 3 percent of white preschool children. These differing exposures to maternal depression could account for a half a point of the assumed eight-point gap in our generic average test score.35