Explaining the Black-White Disparity in Preterm Birth: A Consensus Statement From a Multi-Disciplinary Scientific Work Group Convened by the March of Dimes

Abstract

In 2017–2019, the March of Dimes convened a workgroup with biomedical, clinical, and epidemiologic expertise to review knowledge of the causes of the persistent Black-White disparity in preterm birth (PTB). Multiple databases were searched to identify hypothesized causes examined in peer-reviewed literature, 33 hypothesized causes were reviewed for whether they plausibly affect PTB and either occur more/less frequently and/or have a larger/smaller effect size among Black women vs. White women. While definitive proof is lacking for most potential causes, most are biologically plausible. No single downstream or midstream factor explains the disparity or its social patterning, however, many likely play limited roles, e.g., while genetic factors likely contribute to PTB, they explain at most a small fraction of the disparity. Research links most hypothesized midstream causes, including socioeconomic factors and stress, with the disparity through their influence on the hypothesized downstream factors. Socioeconomic factors alone cannot explain the disparity's social patterning. Chronic stress could affect PTB through neuroendocrine and immune mechanisms leading to inflammation and immune dysfunction, stress could alter a woman's microbiota, immune response to infection, chronic disease risks, and behaviors, and trigger epigenetic changes influencing PTB risk. As an upstream factor, racism in multiple forms has repeatedly been linked with the plausible midstream/downstream factors, including socioeconomic disadvantage, stress, and toxic exposures. Racism is the only factor identified that directly or indirectly could explain the racial disparities in the plausible midstream/downstream causes and the observed social patterning. Historical and contemporary systemic racism can explain the racial disparities in socioeconomic opportunities that differentially expose African Americans to lifelong financial stress and associated health-harming conditions. Segregation places Black women in stressful surroundings and exposes them to environmental hazards. Race-based discriminatory treatment is a pervasive stressor for Black women of all socioeconomic levels, considering both incidents and the constant vigilance needed to prepare oneself for potential incidents. Racism is a highly plausible, major upstream contributor to the Black-White disparity in PTB through multiple pathways and biological mechanisms. While much is unknown, existing knowledge and core values (equity, justice) support addressing racism in efforts to eliminate the racial disparity in PTB.

Vaginal Microbiota, Genital Inflammation and Extracellular Matrix Remodelling Collagenase: MMP-9 in Pregnant Women With HIV, a Potential Preterm Birth Mechanism Warranting Further Exploration

“…The findings of this study would ideally be replicated in a larger cohort, powered to look at differences by prematurity and include racially matched controls. The role of racial disparity in PTB risk is in itself an important question and is likely to be the result of many interplaying factors including: prejudice, genetics, socioeconomics, healthcare access and stress influencing downstream factors such as background co-morbidities, neuroendocrine, infection, microbiota, and immune mediators ( Braveman et al., 2021 ).…”

Racial Disparities in Maternal Health Outcomes: Mental Health Included

“…Although individual behaviors, socioeconomic status, or underlying health conditions are typically identifi ed as drivers of this disparity, data strongly suggest these factors do not adequately explain these diff erences. Increasingly, structural and institutional racism are being called out as the root cause of racial health inequity, including maternal health inequity (Bailey et al, 2017;Braveman et al, 2021;Liu et al, 2019;Taylor, 2020). Structural racism is the harmful, mutually supporting interaction of policies, laws, and norms that perpetuate unfair barriers to education, employment, housing, and health care for people of color (Bailey et al, 2017).…”

“…Th e mental health community, including providers and researchers, has been at the forefront of identifying the lasting physical and psychological eff ects of trauma, such as childhood adverse events. We must also acknowledge the growing evidence of the harmful eff ects of chronic stress due to racism on the bodies and pregnancies of Black women and other women of color (Braveman et al, 2021;Jones et al, 2017;Van der Kolk, 2015).…”

The Toll of Racism on African American Mothers and Their Infants

“…In addition to chronic stress, the March of Dimes work group found many other downstream effects of structural and systematic racism, including exposure to environmental toxins, inadequate medical care, and unhealthy food and exercise, all of which may be more proximal factors that are negatively associated with the health of Black mothers and make preterm births more likely. 6 The lived experience of racism in US-born Black pregnant people may explain several patterns of preterm births among different groups of Black pregnant people. The low incidence of preterm births seen in non-US-born Black pregnant people in the study by Hardeman et al 4 may be explained by their lack of exposure to racism earlier in life, when they would have been more sensitive to the long-lasting impacts of neuroendocrine, epigenetic, and immune dysregulation.…”