摘要：Objectives. We tested the association between 2 measures of childhood socioeconomic position (SEP) and adult body mass index (BMI), stratified by race and ethnicity. Methods. We used regression analyses to examine associations between adult BMI and 2 measures of childhood SEP (maternal education and whether the head of the child's household was working class), adjusted for a robust set of adult SEP measures, in a sample of 2068 adults from Los Angeles County, California. Results. Maternal educational attainment was associated with a lower median adult BMI among Whites (8% decrease for high school diploma and 9% decrease for a college degree, compared with no high school diploma). A maternal high school diploma was associated with a 6% decrease in median adult BMI among Hispanics and an 11% decrease among Blacks. Our measure of childhood working-class status was not correlated with adult BMI. Conclusions. Our results suggest that childhood SEP is independently associated with adult BMI. However, our results also suggest that the effect may depend on which measures of SEP are used and that some aspects of childhood SEP may matter more for adult BMI than others. Levels of obesity and overweight have been on the rise in both developed and developing countries for many years. The US has been a leader in this trend, with steady growth in levels of overweight and obesity since the 1980s. 1 According to 1999 to 2002 data from the National Health and Nutrition Examination Survey (NHANES), the prevalence of overweight and obesity in US adults is at 65%. 2 Since this overall trend began in the late 1970s, several studies have demonstrated that the burden of growing adiposity is disproportionately borne by the economically and socially vulnerable. African Americans and Mexican Americans have higher rates of adiposity than do comparable Whites. The 1999–2002 NHANES data indicate the prevalence of overweight or obesity to be 63% for White adults, 70% for Black adults, and 72% for Mexican American adults. Similarly, individuals with a lower socioeconomic position (SEP) have been shown to be at increased risk for obesity. 3 However, more recent scholarship has complicated the story of this relationship in key ways. First, etiologic research has begun to focus on a life-course perspective to understand these health disparities. A 1999 review article by Parsons et al. reported that among longitudinal observational studies, low childhood SEP was consistently associated with long-term, increased risk of adult adiposity, independent of adult SEP. 4 A recent study using longitudinal data over 34 years also reported an association between low childhood SEP and adult weight gain among women. 5 Second, several key studies have suggested that the effect of childhood SEP on weight may differ by race. Baltrus et al. demonstrated that over a 34-year follow-up, childhood SEP was an important explanatory factor for weight gain, and it lowered the racial disparity in weight gain among women by 30%. 6 Similarly, other studies have indicated that the effect of childhood SEP across the life span may differ by race. An analysis of a representative sample of Australian women indicated that although the effect of low childhood SEP had an independent long-term impact on adult weight, social mobility moderated this effect such that the women began to share the obesity prevalence of their adult SEP group. 7 In comparison, a recent study of African American women found that low childhood SEP was positively associated with obesity regardless of adult SEP. Moreover, the magnitude of this effect was not affected by adult SEP. 8 Together, these studies suggest not only that childhood SEP plays a role in adult adiposity but also that there may be important differences in its effect by race/ethnicity. Another source of complexity stems from the theoretical and methodological measurement of SEP. From some theoretical perspectives, SEP is a latent construct that is a reflection of an individual's position in a given social stratification regime. 9 This theoretical construct is unitary, but empirically speaking, diverse measures of SEP—such as income, education, or occupation—may be differentially influential for specific risk factors or health outcomes. Braveman et al. demonstrated the differential impact of single-item SEP measures in a sample of Black, immigrant Hispanic, and White women. In 10 of the 23 health indicators they examined, they reached different conclusions about the significance, magnitude, or direction of racial/ethnic disparities depending on whether they used education or income as measures of SEP. 10 Other studies have modeled SEP as a latent concept and use composite scores or derived factors to measure it. This option acknowledges the complexity of the concept, but it ignores the possibility that each measure may have an independent effect on health outcomes and may be linked to different causal pathways. 11 The evidence suggests that, for health outcomes, SEP measures should reflect the multifactorial pathways of causation as much as possible. Research using adult SEP has taken this fact into account, but there has been little comparative work on the effects of particular measures of childhood SEP. Efforts to understand the independent role of childhood SEP should be fully attuned to the complexity inherent in the definition and use of socioeconomic measures. Rising population weight can be largely understood as an outcome of population-wide changes in eating and physical activity. Accordingly, differences by SEP can in part be explained by these same mechanisms; solid research has documented that behavioral risk factors for obesity, such as diet 12 , 13 and levels of physical activity, 13 , 14 differ by SEP. However, it is important to gain a better understanding of how this terrain of risk has so quickly become unequally distributed, and how this inequality might differ by race and ethnicity. Therefore, an exploration of how childhood exposure may contribute to these inequalities is an important area of research. Our primary aims were to investigate the association between childhood SEP and adult body mass index (BMI) independent from adult SEP, and to test for race and ethnicity differences in that association by using a diverse sample that included White, Black, and Hispanic adults. Our secondary aim was to take a first step toward deconstructing the measurement of childhood SEP by using 2 measures of childhood SEP: occupational status of the head of household in childhood and mother's level of educational achievement.
