Nativity-Related Disparities in Preterm Birth and Cardiovascular Risk in a Multiracial U.S. Cohort

Risk of Adverse Perinatal Outcomes Among African-born Black Women in California, 2011-2020

BACKGROUND

African-born women have a lower risk of preterm birth and small for gestational age (SGA) birth compared with United States-born Black women, however variation by country of origin is overlooked. Additionally, the extent that nativity disparities in adverse perinatal outcomes to Black women are explained by individual-level factors remains unclear.

METHODS

We conducted a population-based study of nonanomalous singleton live births to United States- and African-born Black women in California from 2011 to 2020 (n = 194,320). We used age-adjusted Poisson regression models to estimate the risk of preterm birth and SGA and reported risk ratios (RR) and 95% confidence intervals (CI). Decomposition using Monte Carlo integration of the g-formula computed the percentage of disparities in adverse outcomes between United States- and African-born women explained by individual-level factors.

RESULTS

Eritrean women (RR = 0.4; 95% CI = 0.3, 0.5) had the largest differences in risk of preterm birth and Cameroonian women (RR = 0.5; 95% CI = 0.3, 0.6) in SGA birth, compared with United States-born Black women. Ghanaian women had smaller differences in risk of preterm birth (RR = 0.8; 95% CI = 0.7, 1.0) and SGA (RR = 0.9; 95% CI = 0.8, 1.1) compared with United States-born women. Overall, we estimate that absolute differences in socio-demographic and clinical factors contributed to 32% of nativity-based disparities in the risk of preterm birth and 26% of disparities in SGA.

CONCLUSIONS

We observed heterogeneity in risk of adverse perinatal outcomes for African- compared with United States-born Black women, suggesting that nativity disparities in adverse perinatal outcomes were not fully explained by differences in individual-level factors.

African immigrants' favorable preterm birth rates challenge genetic etiology of the Black-White disparity in preterm birth

Background

We examined over a million California birth records for 2010 through 2021 to investigate whether disparities in preterm birth (PTB) by nativity and race support the widely held but hitherto unsubstantiated belief that genetic differences explain the persistent Black-White disparity in PTB.

Methods

We examined PTB rates and risk ratios among African-, Caribbean-, and U.S.-born Black women compared to U.S.-born White women. Multivariate analyses adjusted for maternal age, education, number of live births, delivery payer, trimester of prenatal care initiation, pre-pregnancy BMI, smoking, and prevalence of poverty in a woman's residence census tract; and for paternal education.

Results

In adjusted analyses, African-born Black women's PTB rates were no different from those of U.S.-born White women.

Discussion

The results add to prior evidence making a genetic etiology for the racial disparity in PTB unlikely. If genetic differences tied to "race" explained the Black-White disparity in PTB among U.S.-born women, the African immigrants in this study would have had higher rates of PTB, not the lower rates observed. Multiple explanations for the observed patterns and their implications are discussed. Failure to distinguish causes of PTB from causes of the racial disparity in PTB have likely contributed to erroneous attribution of the racial disparity to genetic differences. Based on the literature, unmeasured experiences of racism, including racism-related stress and adverse environmental exposures, are plausible explanations for the PTB disparity between Black and White U.S.-born women. The favorable birth outcomes of African-born Black immigrants may reflect less exposure to racism during sensitive life periods, e.g., childhood, when they were in African countries, where Black people are in the racial majority.

Racial and Ethnic Disparities in Phthalate Exposure and Preterm Birth: A Pooled Study of Sixteen U.S. Cohorts

BACKGROUND

Phthalate exposures are ubiquitous during pregnancy and may contribute to racial and ethnic disparities in preterm birth.

OBJECTIVES

We investigated race and ethnicity in the relationship between biomarkers of phthalate exposure and preterm birth by examining: a) how hypothetical reductions in racial and ethnic disparities in phthalate metabolites might reduce the probability of preterm birth; and b) exposure-response models stratified by race and ethnicity.

METHODS

We pooled individual-level data on 6,045 pregnancies from 16 U.S. cohorts. We investigated covariate-adjusted differences in nine urinary phthalate metabolite concentrations by race and ethnicity [non-Hispanic White (White, 43%), non-Hispanic Black (Black, 13%), Hispanic/Latina (38%), and Asian/Pacific Islander (3%)]. Using g-computation, we estimated changes in the probability of preterm birth under hypothetical interventions to eliminate disparities in levels of urinary phthalate metabolites by proportionally lowering average concentrations in Black and Hispanic/Latina participants to be approximately equal to the averages in White participants. We also used race and ethnicity-stratified logistic regression to characterize associations between phthalate metabolites and preterm birth.

RESULTS

In comparison with concentrations among White participants, adjusted mean phthalate metabolite concentrations were consistently higher among Black and Hispanic/Latina participants by 23%-148% and 4%-94%, respectively. Asian/Pacific Islander participants had metabolite levels that were similar to those of White participants. Hypothetical interventions to reduce disparities in metabolite mixtures were associated with lower probabilities of preterm birth for Black [13% relative reduction; 95% confidence interval (CI): - 34 % , 8.6%] and Hispanic/Latina (9% relative reduction; 95% CI: - 19 % , 0.8%) participants. Odds ratios for preterm birth in association with phthalate metabolites demonstrated heterogeneity by race and ethnicity for two individual metabolites (mono-n-butyl and monoisobutyl phthalate), with positive associations that were larger in magnitude observed among Black or Hispanic/Latina participants.

CONCLUSIONS

Phthalate metabolite concentrations differed substantially by race and ethnicity. Our results show hypothetical interventions to reduce population-level racial and ethnic disparities in biomarkers of phthalate exposure could potentially reduce the probability of preterm birth. https://doi.org/10.1289/EHP12831.

Health Experiences of African American Mothers, Wellness in the Postpartum Period and Beyond (HEAL): A Qualitative Study Applying a Critical Race Feminist Theoretical Framework

The objective of this study is to explore the cultural, social, and historical factors that affect postpartum primary care utilization among Black women with cardiometabolic risk factors and to identify the needs, barriers, and facilitators that are associated with it. We conducted in-depth interviews of 18 Black women with one or more cardiometabolic complications (pre-pregnancy chronic hypertension, diabetes, obesity, preeclampsia, or gestational diabetes) within one year of delivery. We recruited women from three early home-visiting programs in Baltimore, Maryland, between May 2020 and June 2021. We used Critical Race Feminism theory and a behavioral model for healthcare utilization as an analytical lens to develop a codebook and code interview transcripts. We identified and summarized emergent patterns and themes using textual and thematic analysis. We categorized our findings into six main themes: (1) The enduring influence of structural racism, (2) personally mediated racism in healthcare and beyond, (3) sociocultural beliefs about preventative healthcare, (4) barriers to postpartum care transitions, such as education and multidisciplinary communication, (5) facilitators of postpartum care transitions, such as patient-provider relationships and continuity of care, and (6) postpartum health and healthcare needs, such as mental health and social support. Critical race feminism provides a valuable lens for exploring drivers of postpartum primary care utilization while considering the intersectional experiences of Black women.

Black Nativity and Health Disparities: A Research Paradigm for Understanding the Social Determinants of Health

After more than a century of research and debate, the scientific community has yet to reach agreement on the principal causes of racialized disparities in population health. This debate currently centers on the degree to which "race residuals" are a result of unobserved differences in the social context or unobserved differences in population characteristics. The comparative study of native and foreign-born Black populations represents a quasi-experimental design where race is "held constant". Such studies present a unique opportunity to improve our understanding of the social determinants of population health disparities. Since native and foreign-born Black populations occupy different sociocultural locations, and since populations with greater African ancestry have greater genetic diversity, comparative studies of these populations will advance our understanding of the complex relationship between sociocultural context, population characteristics and health outcomes. Therefore, we offer a conceptual framing for the comparative study of native and foreign-born Blacks along with a review of 208 studies that compare the mental and physical health of these populations. Although there is some complexity, especially with respect to mental health, the overall pattern is that foreign-born Blacks have better health outcomes than native-born Blacks. After reviewing these studies, we conclude with suggestions for future studies in this promising area of social and medical research.