A new study found that the prevalence of preterm birth varied significantly by region and country of origin among Black parents in Massachusetts. These differences were not explained by socioeconomic, health, and behavior characteristics, and suggest that other social factors, such as exposure to racial discrimination, may be a fundamental cause of racial inequities in preterm birth.
Despite persistent research and interventions, racial inequities in preterm birth (PTB) continue to widen in the United States, impacting non-Hispanic Black infants at almost twice the rate (14 percent) of non-Hispanic White babies (9 percent). And among Black birthing people, current research shows that those who are foreign-born are less likely to have a PTB than their US-born counterparts.
However, a closer look at Black PTB rates reveals that the prevalence of PTB among Black immigrants varies widely by nativity, region, and country of origin, according to a new study led by a Boston University School of Public Health (BUSPH) researcher.
Published in the Maternal and Child Health Journal, the findings suggest that failing to disaggregate by these factors can mask variation in social experiences, history, and health, and thus underestimate inequities in Black PTB rates.
The study examined natality data from 2011 to 2015 in the three largest cities in Massachusetts, a state that has a large population of foreign-born Black residents. The study showed that while foreign-born birthing parents from Sub-Saharan Africa have a lower risk of PTB than US-born Black parents, Caribbean and Brazilian immigrants experience PTB on par with US-born Black parents.
Notably, the study also observed a wide variation in individual demographic, behavior, and health factors between US and foreign-born Black parents, but found that these factors did not explain the inequities in PTB among the two groups. Other social factors, such as differences between the two groups in experiences with racism-;a documented risk factor for PTB-;may contribute to these inequities.
"The importance of disaggregating health inequities data wherever possible cannot be overstated," says study lead author Dr. Candice Belanoff, clinical associate professor of community health sciences at BUSPH. "Race is not a meaningful biological construct that could be reasonably associated with preterm birth." Interpersonal and structural racism, however, are different matters, she says. "People come to the US from all over the world, carrying with them not only their own individual life experiences and exposures, but often intergenerational trauma from the legacies of colonization and enslavement. These are the factors we need to examine if we hope to understand racial inequities in perinatal outcomes."
For the study, Belanoff and colleagues examined associations between PTB and nativity, region, and 18 individual countries of origin among 28,290 births, and then adjusted for individual-level risk factors such as marriage status, education, smoking history, access to prenatal care. PTB was higher among US-born Black birthing parents (9.4 percent) than foreign-born Black birthing parents (7.7 percent)-;but the PTB rates among Black birthing parents from the Caribbean were only slightly lower than US rates, at 9.2 percent. Among foreign-born Black parents, those from Sub-Saharan Africa had the lowest rates, at an average of 6.6 percent, but even those figures varied widely depending on the country or origin, ranging from 4 percent among birthing parents from Angola to 10.6 percent among those from Sierra Leone.
This wide variation dispels the phenomenon known as the "immigrant health advantage," which suggests that immigrants have better birth outcomes than those in the US, and it also builds upon prior research that indicates that US-born and foreign-born Black people have different levels of exposure to racism and discrimination, which has a documented impact on physical and mental health. Past studies have shown that self-reported racism is higher among US Black women than foreign-born Black women, and that foreign-born Africans-;but not Caribbean-born women-;reported substantially lower rates of discrimination than US-born Black women.
The researchers say these differences warrant further research to understand and prevent racial inequities in PTB.
Having systemic data on experiences of discrimination and exposure to racism is the first step in understanding how much it accounts for inequities in maternal and infant health outcomes across race, ethnicity and other socially marginalized groups."
Joanne Almeida, study senior author, associate professor, Simmons School of Social Work
Almeida also served as lead author, along with Belanoff as a co-author, of a commentary published last year in MCH that called for the Centers for Disease Control and Prevention to implement a validated measurement to assess the impact of discrimination in the Pregnancy Risk Assessment Monitoring System, its annual state-level questionnaire.
The CDC recently responded to the commentary in a Letter to the Editor published in MCH, in which they stated that the agency "is engaged in the process of developing a special questionnaire supplement on Social Determinants of Health and a new Phase 9 version of the questionnaire."
Belanoff, C., et al. (2022) Preterm Birth Among US and Foreign-Born Non-Hispanic Black Birthing Parents in Massachusetts: Variation by Nativity, Region, and Country of Origin. Maternal and Child Health Journal. doi.org/10.1007/s10995-021-03368-0.