A new University of Minnesota study has found that the anxiety of living in Minneapolis neighborhoods with a larger police presence may put pregnant mothers at greater risk of preterm delivery.

Authors of the report, published earlier this month in the Journal of the American Medical Association (JAMA) Open Network, said it's the first study to look at how exposure to such stressors can lead to greater risk of preterm birth — giving birth before 37 weeks of pregnancy, which can lead to serious health complications for babies. Researchers found that while both Blacks and whites in those neighborhoods both experienced adverse effects, more "Black birthing people" tended to live in areas that had historically been over-policed.

This finding, the study's authors say, adds to a growing body of research showing the psychological and health costs of policing on certain communities, particularly Black Americans.

"Racism is a fundamental cause of health inequity, which means we have to apply antiracism to institutions that affect the fundamentals of our lives and communities," U associate professor Rachel Hardeman said in a university news brief. Hardeman is director of the SPH Center for Antiracism Research and Health Equity (CARHE) and a leading expert on racial reproductive health disparities. "Our research focused on residents of Minneapolis and found that U.S.-born Black birthing people and their babies were hit the hardest by over-policing, which is a form of structural racism."

Drawing on medical and police records, Hardeman and her research colleagues found that the exception was among Black mothers born in another country, who showed only a 10% higher chance for early birth — compared to 100% and 90% for U.S.-born mothers and white mothers, respectively. One possible explanation is what researchers dubbed the "immigrant paradox:" the idea that Black immigrants who didn't grow up experiencing structural racism have better health outcomes than U.S.-born Blacks.

"Racism is a fixable problem," said Hardeman. "Community health needs to be a priority for public safety reform, and the voices and needs of Black, Indigenous, and people of color need to be prioritized."

The study's authors pointed to the need for longitudinal research around the subject, including in cities like New York, Chicago and Seattle with larger Black immigrant populations. They also mentioned statistical limitations in their study, such as the difficulty of determining whether study participants had contact with police before or during pregnancy or whether participants lived at the same address for the duration of the study. Another complicating factor was trying to disentangle community-level police contact from "other forms of structural racism that cannot be assessed in this study," the authors wrote.

Racism, the study's authors said, "shows up in many ways in our society." For on thing, due to residential segregation Black people have historically been to neighborhoods disproportionately affected by poverty, violence and crime — which has historically led to aggressive, broken windows-style policing, researchers said. At the same time the study builds on previous research showing that Black people already are nearly twice as likely to experience a preterm birth as white people.

"Police contact—specifically routine stops conducted by police departments as a crime deterrent measure in certain neighborhoods—signal to Black people that in the eyes of the law, they are seen as inherently criminal and dangerous. This negative socialization coupled with the aggressive behavior that officers exhibit during these stops increases stress, anxiety, and adverse physical health for people living in these communities," researchers wrote. "Now more than ever, communities across the country are grappling with how to ensure public safety in light of racialized incidents of police brutality brought to their awareness in the aftermath of the murder of George Floyd, Jr, in Minneapolis, where this study took place."