The findings add to growing evidence that racial discrimination is a risk factor for poor health outcomes, say the researchers.

For several decades, race has been recognised as a social determinant of health and a risk factor for numerous diseases. The evidence increasingly suggests that social, environmental, economic and political factors are fundamental drivers of health inequities, and that it is often racial discrimination or racism, rather than race, that is the root cause of racial disparities in health outcomes.

For example, maternal death rates among Black and Indigenous women in the USA are two to three times higher than those of white women. Similarly, in the UK, maternal death rates are two to four times higher among Black and Asian women compared to death rates among white women.

To explore the existing patterns of racial discrimination and adverse pregnancy outcomes, the researchers carried out a systematic review and meta-analysis, pooling and analysing data from the available evidence. This approach allowed them to bring together existing and sometimes contradictory or under-powered studies to provide more robust conclusions. Their results are published in the open access journal BMJ Global Health.

The team searched eight electronic databases, looking for relevant studies on self-reported racial discrimination and premature birth (that is, before 37 weeks), low and very low birthweight, small-for-gestational age, and high blood pressure associated with pregnancy.

In all, the results of 24 studies were included in the final analysis. The majority of studies (20) were carried out in the USA. Study participants were of different racial and ethnic backgrounds, including Black or African American, Hispanic, non-Hispanic white, Mãori, Pacific, Asian, Aboriginal Australian, Romani, indigenous German and Turkish.

The pooled analysis showed that the experience of racial discrimination was significantly associated with increased risk of premature birth. Women who experienced racial discrimination were 40% more likely to give birth prematurely. When low quality studies were excluded, the odds of a premature birth were reduced, but still 31% higher in those experiencing racial discrimination.

While not statistically significant, the results also suggest that the experience of racial discrimination may increase the chance of giving birth to a small-for-gestational age baby by 23%.

Co-first-author Jeenan Kaiser, who did her MPhil in Public Health at the University of Cambridge and is currently a medical student at the University of Alberta, said: “Racial discrimination impacts the health of racialised communities not only in direct and intentional ways, but also in how it shapes an individual’s experiences, opportunities, and quality of life. These are fundamentally driven by structural and social determinants of health.

“While our study focused on its impact on pregnancy outcomes, it is becoming increasingly evident that it negatively impacts a myriad of health outcomes. Efforts to counter racial discrimination and promote health must focus on systemic policy changes to create sustainable change.”

Co-first author Kim van Daalen, a Gates Cambridge and PhD candidate at the Department of Public Health and Primary Care, University of Cambridge, said: “Dismantling structures and policies that enable institutional and interpersonal racial discrimination, underlying racial and ethnic disparities in health and intersecting social inequalities, is essential to improve overall health in societies. Partnerships of health care professionals with community-based reproductive justice and women’s health organisations who work in this area can improve health for racialised women in a community-centred way.”

The researchers point out that racial discrimination impacts what health services and resources are available, such as referral to specialist care, access to health insurance and access to public health services.

Co-author Dr Samuel Kebede, who did his MPhil in Epidemiology at the University of Cambridge as a Gates Cambridge Scholar and is currently at Montefiore Health System/Albert Einstein College of Medicine in New York City said: “Historically there have been countless examples of where medicine and public health have been furthered by the subjugation and experimentation of Black and indigenous people. But the influence of structural racism is still present within the healthcare system today. From segregated healthcare for uninsured and under-insured people of colour in the United States, to the global disparity in COVID-19 vaccinations, structures continue to perpetuate inequities. Health professionals can play a vital role in dismantling these systems.”

Many of the studies were of limited quality and included few marginalised racial or ethnic groups other than African Americans; as such, their applicability to other ethnic groups and cultural settings may be limited. However, the researchers argue that when pooled, the data clearly demonstrate the negative impact of racial discrimination on pregnancy outcomes.

Reference van Daalen, KR, & Kaiser, J et al. Racial discrimination and adverse pregnancy outcomes: a systematic review and meta-analysis. BMJ Global Health; 3 Aug 2022; DOI: 10.1136/bmjgh-2022-009227