The Association of Preterm Birth With Maternal Nativity and Length of Residence Among Non-Hispanic Black Women

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.

Nativity and perinatal outcome disparities in the United States: Beyond the immigrant paradox

In the United States (US), epidemiologists have long documented paradoxically lower rates of adverse perinatal health outcomes among immigrant birthing people than what might be expected in light of socioeconomic and language barriers to healthcare, especially as compared to their US-born racial and ethnic counterparts. However, researchers have also documented significant variability in this immigrant birth paradox when examining within and across racial and ethnic subgroups. This review paper summarizes fifty years of research regarding differences in low, preterm birth, and infant mortality in the US, according to the nativity status of the birthing person. While there is ample evidence of the importance of nativity in delineating a pregnant person's risk of adverse infant outcomes, this review also highlights the relative paucity of research exploring the intersection of acculturation, ethnic enclaves, and structural segregation. We also provide recommendations for advancing the study of perinatal outcomes among immigrants.

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.