It is well documented that Black women in the U.S. experience inequities in maternal and child health outcomes. The mortality rate for Black newborns is approximately twice that of babies born to non-Hispanic white mothers in the U.S, and Black women are more than 50% more likely to deliver a premature baby. And research has shown that these disparities are not the result of intrinsic differences between racial groups, but due to systemic racism.
Now, new research findings from Boston Medical Center (BMC) show that birthing people born in the United States have an increased risk of experiencing adverse perinatal outcomes—including preterm birth, hypertensive disorders, low birth weight, and NICU admission—compared to patients born outside of the U.S. but cared for in the country. The study emphasizes the racial and ethnic disparities in birth outcomes and the impact of race-based inequities and racism in healthcare within the U.S.
Research suggests deleterious effects of racism on U.S.-born mothers
Published in the Maternal and Child Health Journal, the results show an impact of nativity, or place of birth, on the outcomes overall for all mothers and their babies. But that impact is not uniform. While birth outside the U.S. was protective for white and Hispanic mothers and infants, Black mothers consistently experienced the most pronounced adverse outcomes, regardless of birthplace.
Researchers studied a large sample of 11,097 BMC patients, 3,476 who were born in the U.S. and 7,621 who were foreign-born, including naturalized citizens, temporary migrants, refugees, asylum-seekers, undocumented immigrants, and permanent residents with varying lengths of stay in the U.S. The study was done using the electronic health records of all births of at least 20-week gestation that occurred from January 1, 2010 to March 31, 2015 at BMC.
There was an overall increase of risk to birthing people born in the U.S. compared to abroad. Study results showed that 10.6% of patients born in the U.S. experienced preterm birth compared to 8.2% of foreign-born patients. The prevalence of early preterm birth (at or before 32 weeks of pregnancy) and low birth weight at term were more than twice as high for those born in the U.S.
"While birth outside the U.S. was protective for white and Hispanic mothers and infants, Black mothers consistently experienced the most pronounced adverse outcomes, regardless of birthplace."
But among people giving birth who were born in the U.S., Black patients experienced a 22% higher prevalence of hypertensive disorders, 28% higher prevalence of preterm birth, and 83% increased prevalence of early preterm birth compared to white patients.
"Differences in birth outcomes based on maternal birthplace do not uniformly apply when race and ethnicity are considered," says Tejumola Adegoke, MD, MPH, an obstetrics & gynecology physician and director of equity and inclusion at Boston Medical Center. "Our data suggests that the health advantage previously noted among migrants to the United States is attenuated for Black birthing people and their children. This underscores the impact of race-based discrimination and differences in care. As we understand the factors that impact maternal inequities better, we can use that to combat disparities and improve outcomes for all women."
Consistent inequitable pregnancy outcomes for Black women
The prevalence of preterm birth was highest among U.S.-born Black patients at 12%, and U.S.-born Hispanic patients at 10%. However, the largest association between being U.S.-born and experiencing adverse outcomes was among white patients, where there was a 40% increased prevalence of hypertensive disorders and similar prevalence of preterm delivery, diabetes, and cesarean delivery and NICU admission.
Researchers speculate that this is driven by disproportionately higher rates of substance use disorder (SUD) among U.S.-born white women in the BMC sample. The retrospective study of patients includes a large cohort of women with SUD, who have been noted to have a higher risk of maternal and neonatal morbidity. For this study, researchers used a sensitivity analysis to exclude women with SUD and found that the disparity between U.S.-born Black and white patients widens substantially. Since substance use in pregnancy is known to adversely impact birth outcomes, this analysis demonstrates the true extent of the racial inequity in this study population, which might otherwise be obscured.
Among those who were foreign-born, Black patients delivering babies still had a higher prevalence of many maternal and neonatal complications, while Hispanic patients had a lower prevalence of complications, compared to white. Black birthing people and infants consistently experienced worse outcomes regardless of their nativity, while foreign-born Hispanic patients experienced less disparate outcomes.
Future research should continue to assess the best practices for addressing modifiable risk factors for perinatal outcomes, including systemic racism and disparate care provisions. According to the study authors, the focus should be on innovative interventions targeted to at-risk populations.
"The system of race-based segregation and discrimination in the United States affects access to all social and economic resources, including healthcare," says Adegoke. "Individuals who have lived outside of this system for some time may temporarily avoid the cumulative effect of racism and its related stress on their health, but for Black women, the effect on maternal mortality and perinatal outcomes is seemingly inescapable."