Preterm birth, defined as a live birth before 37 weeks of pregnancy, is the second-leading cause of infant mortality in the United States, and one that disproportionately affects Black and Hispanic birthing people. While individual-level factors such as poverty, age, and health status may contribute to racial/ethnic disparities in preterm birth, researchers believe there are broader structural challenges that may be driving the racial gap in this all-too-common birth complication.

A new study led by Boston University School of Public Health (BUSPH) examined preterm births in Massachusetts, where 1 in 11 live births are premature, and found that the social characteristics of a birthing parent’s neighborhood is associated with their risk of experiencing an early delivery.

Published in JAMA Network Open, the study found that more than half of Black and Hispanic infants were born into very low-opportunity neighborhoods, and that babies born into these neighborhoods had a 16-percent greater risk of being born preterm. Researchers assessed neighborhood opportunity level based on a variety of educational, health, environmental, and socioeconomic characteristics identified in the Childhood Opportunity Index (COI), a widely used composite measure that currently includes 44 indicators by census tract.

The study sheds new light on the health consequences of structural racism and historically discriminatory practices — such as redlining and disproportionate exposures to pollutants — that continue to shape modern-day neighborhood conditions and circumstances. Because neighborhood social opportunity is inequitably distributed by race and ethnicity, the COI serves as a valuable measure of both historic and ongoing structural racism, the researchers say.

“Our findings suggest that the context of social opportunity has an impact on children’s health before they are even born, and may in part be a driver of persistent racial and ethnic inequities in preterm birth,” says study lead and corresponding author Dr. Candice Belanoff, clinical associate professor of community health sciences at BUSPH. “The effect remained after we controlled for factors such as maternal/birthing parent health and individual social position.”

Dr. Belanoff and colleagues from BUSPH, Simmons SSW, the University of Illinois, Chicago (UIC), and Brandeis University (Brandeis) utilized Massachusetts birth certificate data by census tract for more than 260,000 singleton infants born in the Boston, Springfield, and Worcester metropolitan areas from February 2011 to December 2015, to explore possible links between neighborhood opportunity levels and preterm births.

Preterm birth was highest among Black infants at 8.4 percent, followed by Hispanic infants at 7.3 percent, Asian or Pacific Islander infants at 5.8 percent, and White infants at 5.8 percent. Compared to White and Asian or Pacific Islander infants, Black and Hispanic infants were approximately 54 percent more likely to be born into very low child opportunity neighborhoods, compared to White infants (11.8 percent) and Asian or Pacific Islander infants (19.6 percent) Similarly, Black and Hispanic infants were also least likely to be born into very high child opportunity neighborhoods, at 6 percent and 6.7 percent, respectively.

“While many lower opportunity neighborhoods are rich cultural hubs and locations of incredible community activism and power, they still suffer the effects of economic exclusion, they are still closer to toxic environmental exposures, and they still generally feature fewer of the resources that help people flourish across the life course,” Dr. Belanoff says.

“This is why it is important to look beyond the individual if we are ever going to reduce or eliminate the racial/ethnic gap in birth outcomes,” says study senior author Dr. Joanna Almeida, professor and Eva Whiting White Endowed Chair at Simmons SSW. “We need to address the inequitable distribution of resources and access to neighborhood opportunity in order to move the needle on racial and ethnic inequities in preterm birth.”