The main findings of this study are that perceived racism across the lifetime and perceived racism vicariously experienced as a child predict birth weight in African Americans and help to account for racial differences in birth weight, controlling for medical and sociodemographic risk factors. Although perceived racism's association with birth weight outcomes has been reported previously in the literature, including attenuation of racial differences (e.g., Mustillo et al., 2004
), none of the prior racism and pregnancy studies, to our knowledge, have explicitly examined racism exposure in childhood or direct versus vicarious experiences, and none have included an “other” domain to capture as many events as possible or considered as broad an array of socioeconomic factors. Thus, our results not only lend further empirical support to a link between perceived racism and birth weight, but they also provide richer and more detailed insights into their possible connection.
The fact that a third of Whites perceived that they had been the direct target of unfair treatment because of race is a somewhat surprising statistic, but it is fairly comparable with White rates reported in other studies (e.g., Krieger et al., 2005
; Mustillo et al., 2004
), is less than a majority, and is considerably lower than that for African Americans, in accordance with hypothesized racial differences. In addition, the African Americans and Whites studied here exhibited a similar pattern of association between perceived racism and the other stress variables (for Whites, r
s ranged from .24 for pregnancy anxiety to .44 for stressful life events; for African Americans, r
s ranged from .29 for pregnancy anxiety to .53 for stressful life events), suggesting that racism is a form of stress that can be validly assessed in both groups. Indeed, if racism's role in health disparities is of scientific interest, then measuring it in Whites, as well as people of color, is a scientific imperative (Landrine et al., 2006
). That the groups did not exhibit similar patterns of association between racism and birth outcomes is likely a function of vast differences in their sociopolitical histories. Gee (2002)
posits that racism's influence is threshold dependent and that African Americans' level of exposure is high enough, given their pervasive and long-standing experience of discrimination, to trigger both mental and physical health consequences.
A particularly notable finding of this research is that racism vicariously experienced in childhood, most often via a parent or guardian, was the only component of the perceived racism lifetime score that was a significant independent predictor of birth weight, even after using the most stringent controls for SES. This finding underscores the critical need to examine the developmental context within which racism is experienced, as certain periods of the life course may be more sensitive to racism than others. From an attachment perspective, children's sense of security and emotional stability is inextricably linked to their parents' well-being (Sroufe, 1996
); therefore, threats to the parents are likely to be quite salient and personally threatening to the child. From a socialization standpoint, many African American parents believe they must arm their children against racial discrimination by cultivating pride in their ethnic heritage, as well as by exposing them to the horror and injustice of racism, past and present (Hughes et al., 2006
). Despite parents' protective intentions, certain racial messages might heighten children's threat perception and inadvertently trigger chronic states of hyperarousal (Hughes et al., 2006
). Repetti, Taylor, and Seeman (2002)
argued that exposure to highly threatening situations in childhood may generate stress-induced emotional and physiological changes that have long-range mental and physical health consequences. At the same time, our findings for lifetime perceived racism suggest that the accumulation of racism stress across the life course should be considered as well. Lu and Halfon (2003)
proposed a health trajectory model of racial disparities in birth outcomes that conceptualizes reproductive health longitudinally by combining sensitive periods of development with the cumulative toll of adaptation to stressors.
In contemplating the findings reported here, it is important to consider the limitations of the study. This study design excluded women who reported smoking cigarettes or using drugs or alcohol. Such women are not only at higher risk for poor pregnancy outcomes, but they may also be using substances as a way of coping with stress. In addition, the African American and White women studied here were of higher than average SES than their respective groups in the general population, and they were getting early and regular prenatal care. Thus, our sample is likely to represent a healthier subset of pregnant women, both psychosocially and physically. This could explain the absence of some hypothesized racial differences in general and pregnancy stress, as this sample had greater socioeconomic resources than our previous samples (e.g., Feldman et al., 1997
; Zambrana et al., 1999
). The higher SES of the sample may also be a reason we found few associations between birth outcomes and the more traditional stress variables.
Another issue concerns assessment of the different stress variables. Because it was measured over the life course, perceived racism may have been a more robust stress predictor than the general and pregnancy stress variables, whose time frames were focused on the perinatal period. Although we based our perceived racism measure on existing literature on the issue, our measure is still an imperfect indicator of perceived exposure to racism and does not assess specific racism events, the emotional distress associated those events, the frequency with which they occur, or the stress associated with knowing that as a racial minority the possibility always exists that one will be discriminated against. An additional limitation of our measure of racism was its exclusive focus on perceived interpersonal experiences. Institutional forms of racism (e.g., Massey & Denton, 1993
; Smedley, Sith, & Nelson, 2003
), in contrast, are concealed in the day-to-day operation of systems and pose a macro-level threat to health regardless of personal perception (Clark et al., 1999
). Although studies of racism and health are proliferating, very few have incorporated measures of racism at both the interpersonal and the institutional levels, although both forms have been shown to independently affect health outcomes when studied concurrently (e.g., Gee, 2002
The major findings of this study involve racial differences in continuous levels of birth weight. The largest adjusted difference in birth weight between non-Hispanic Whites and African Americans was 340.55 g, or 0.75 lb. Although seemingly trivial, this difference holds important clinical implications. Variations in normal-range birth weight have been associated in large-scale studies with several indicators of child health and development (Institute of Medicine, 2006
), including cognitive function (Richards, Hardy, Kuh, & Wadsworth, 2001
), ocular development (Saw et al., 2004), and school performance (Kirkegaard, Obel, Hedegaard, & Henriksen, 2006
), independent of confounding factors. Moreover, this finding was evident in a relatively healthy sample of pregnant women with disproportionately low-risk pregnancies and above-average levels of education and income. That racial differences would persist in this context is most notable. Even more interesting, perceived racism predicted 6% additional variance in birth weight in African American women, suggesting that it may be a particularly potent type of stress with important consequences for African American women's reproductive health, regardless of whether their pregnancies culminate in an adverse outcome. Thus, this study's prediction of gradations in normal birth weight is clinically relevant, despite its focus on subclinical levels of birth outcomes.
The racial disparity in adverse birth outcomes is a public health conundrum that continues to challenge the medical and academic communities. The results of this study demonstrate that perceived racism is a significant predictor of African American birth weight and a significant mediator of racial differences in birth weight. These findings further suggest that a life course approach could prove particularly useful for identifying risk factors and etiological processes early in the life trajectory that are involved in these specific health outcomes.