In this analysis, we found that individual experiences of racial discrimination and income and racial polarization measured by the ICE index were significantly associated with gestational age at birth in a sample of nulliparous women in the U.S. We also found that EOD moderated the association between racialized residential segregation and gestational age at birth. Our findings are in line with previous studies examining associations between individual- and structural-level racism separately and adverse birth outcomes.1,10,23 We extend previous work by examining the association between individual and structural racism together with gestational age, and by extending analyses to include Hispanic women.
In comparison to pregnant women living in the higher income concentration of households, those who lived in households concentrated in deprivation had infants born at significantly earlier gestational ages. We found that about 17% of NH Black women and 10% of Hispanic women in nuMoM2b had ever experienced racial discrimination in at least three social situations, and that higher EOD scores were significantly associated with shorter gestational age at birth for NH Black women only. The significant association between structural level racism and gestational age became insignificant after accounting for maternal race, which indicated the magnitude of associations between this racism measure and gestational age did not differ by race. This reveals the detrimental effects structural racism could have on all races. However, NH Black and Hispanic women were more likely to experience interpersonal discrimination or be treated unfairly, and were more likely to birth infants at earlier gestational ages compared to NH White women.
Public Health Implications
There is a paucity of studies examining the effects of both structural and individual racism on health outcomes and the experiences of racism and discrimination and adverse pregnancy outcomes among Hispanic women. One qualitative study of Puerto Rican women in Connecticut (n = 29) examined stressors including racial and ethnic discrimination, finding that poverty, food insecurity, low quality education and unsafe environments contributed to poor maternal and child health conditions.24 Another study compared Black (n = 1,154) and Latina (n = 578) women from the Community Child Health Research Network Study, and found that Latina women who experienced everyday racism a few times a month (medium exposure category) had a higher risk of PTB (adjusted hazard ratio (aHR) = 4.1 (95% CI 1.1–15.5), but no significant relationship was observed among Black women in that study (aHR = 1.5, 95% CI 0.8–2.9).25 Others reported a significant relationship between experiences of discrimination and low birthweight among Latina (n = 262) and Black (n = 158) young women in New York City, however, Latina women were not examined separately.26
We also found no significant differences in gestational age at birth for Hispanic women compared to NH White women despite their socioeconomic disadvantage which could be a demonstration of the “Hispanic paradox”, which refers to the seemingly contradictory finding that, despite facing socioeconomic disadvantages, Hispanic individuals in the U.S. tend to have better health outcomes than NH Whites.27 A large proportion of Hispanic women in this study were from Mexico, but also many participated had other countries of origin. It is possible that the protective effects cited in previous work supporting the Hispanic paradox in Mexicans may have been offset by combining Mexican women in nuMoM2b with women from other countries. Previous work suggests that the Hispanic paradox may not be a universal phenomenon across all Hispanic subgroups, with worse birth outcomes reported in women with Dominican or Puerto Rican heritage.28 However, it is difficult to interpret our study findings in the context of the Hispanic paradox as Hispanic women had birth outcomes that were comparable to NH White women. This could also be explained by the almost even distribution of women in the second generation in the U.S., or due to more social support received by Hispanic women living in multi-generational households.29,30
Shorter gestation is one of the most important predictors of infant health and mortality.31 Our findings convey the complex role of individual and structural racism on inequalities in birth outcomes. Individual experiences with discrimination and increased levels of stress associated with these experiences have also been shown to have detrimental effects on birth outcomes.8 The income and racialized residential segregation captured by the ICE measure demonstrated injustices within communities through systematic racism and discrimination which have been shown to contribute to persistent health inequities and disparities that continue to impact communities of minoritized women today.1,3,10 Thus, examination of these measures is important as they are tied to potential interventions to resolve the health impacts of social inequalities and health disparities. More work is required to further examine the multidimensional nature of racism and its effects on gestational age and birth outcomes. Future research should also focus on experiences of racism and discrimination among Hispanic women, by geographic area of origin, and include measures of acculturation and other factors that may contribute to poor outcomes.
This study builds upon previous findings on racism and pregnancy outcomes by examining the impact of structural racism and individual experience of racism while accounting for individual-level characteristics. Our study also had limitations. We conducted a cross-sectional study, limiting our ability to account for changes in exposure to racism and segregation patterns over time. However, the results from this study offer a glimpse into the impact of racism and discrimination experiences on gestational age at birth. Future studies should examine the effects of exposure to structural racism and individual experiences of racism across the lifetime using longitudinal datasets. Such datasets will be available soon as nuMoM2b is continuing to follow the cohort as part of the National Heart, Lung, and Blood Institutes Heart Health Study (HHS). Secondly, it is important to note that the low percentage of NH Black and Hispanic women in the study may limit the generalizability of the findings. In addition, our study is limited by incomplete data on the length of time the women resided in their neighborhoods, which is an important factor to consider since the impact of exposure to unfavorable socioeconomic conditions throughout the lifetime and even across generations may lead to racial disparities in preterm birth and other adverse birth outcomes.32–35 Finally, the primiparous women in nuMoM2b were healthy, low-risk, and had the means and agreed to participate in an intensive, longitudinal study. These characteristics may not be representative of the larger populations, and underscore the need for more longitudinal studies in pregnancy that focus enrollment on NH Black and Hispanic women, with considerable heterogeneity within their own racial and ethnic groups to more accurately study — and identify — reasons for disparities in adverse birth outcomes.
We have shown that individual experiences of racial discrimination and income and racial polarization are significantly associated with gestational age at birth in a sample of nulliparous women in the U.S. Further research is needed, including improved conceptualization of multilevel racism in studies examining racial and ethnic disparities in adverse birth outcomes. These studies should include a greater representation of heterogenous NH Black and Hispanic women to better understand this complex relationship.