African-American women are nearly twice as likely to give birth prematurely as white women. Such births often coincide with low birth weight, and together are linked to other developmental delays and health effects believed responsible for almost one-fifth of infant deaths nationwide.

The trend holds up regardless of socioeconomic factors. That means, for example, that a black woman with a college degree and a comfortable income has a greater chance of giving birth prematurely than a white woman who didn't graduate high school.

Past research has pointed to other contributing factors to the difference, such as post-traumatic stress disorder. In a paper in the winter issue of the Journal of Health Disparities Research and Practice, Amelia Gavin, an associate professor in the University of Washington School of Social Work, connects racial discrimination to PTSD, and thus to preterm birth.

"Pregnancy is a stress test for the body. If you've been stressed during your life through discrimination, poverty and residential segregation, then the likelihood of having a healthy birth outcome has been compromised," Gavin said.

A typical pregnancy lasts about 40 weeks; a birth before the end of the 37th week is considered "preterm." According to the Centers for Disease Control and Prevention, 10 percent of babies born in the U.S. in 2016 were born prematurely - a slight uptick that year, following a steady decline for several years prior. While the CDC attributed that decline to the decrease in the number of teen mothers, the agency noted a consistent difference in the rates of preterm birth among African-American versus white women. In 2016, the preterm birth rate among African American women was 14 percent, compared to 9 percent for white women. There are medical causes of preterm birth, "but the majority of cases have an unknown cause," Gavin said.

Research over the years has examined behavioral and biological risk factors for preterm birth, including access to prenatal care, substance use and stress. PTSD, associated not only with combat experiences, but also other traumatic events such as natural disasters, assault and abuse, affects more women than men. Several studies have linked PTSD with a higher risk of preterm birth.

When broken down by race and ethnicity, PTSD affects African-Americans more than any other group, and more African-American women than men.

Meanwhile, studies have tied racial discrimination to poor health, and to African-American women's health, in particular. The daily experiences of discrimination, as well as the legacy of racism - neighborhoods with higher crime and fewer resources, generational poverty and limited access to health care - can lead to stress, and engagement in unhealthy behaviors.

Gavin drew a hypothesis from those connections: If discrimination is associated with PTSD, and PTSD is associated with preterm birth, then racial discrimination, via PTSD, also can be tied to preterm birth.

The racial disparity among preterm birth sparked her research interest in graduate school, Gavin said. By studying childhood poverty and abuse, as well as maternal depression, Gavin honed in on PTSD.

"I'm trying to unpack, from a life course perspective, how risk factors in black women's lives can have an impact on the next generation," she said. "Exploring the mechanisms by which racial discrimination affects the next generation is really important, and that means taking into consideration maternal mental health status. When we talk about racial disparities in health outcomes, we have to think about how we construct mental health, the role of PTSD and how different racial and ethnic groups experience it."

One challenge has been how PTSD is defined, generally by members of the mental health community, Gavin said. PTSD isn't always related to one physically or emotionally devastating event; events can recur and continue to affect a person over the long term. There has been little research into how racial discrimination could manifest as PTSD and influence an early childbirth, she said.

Further research could more definitively demonstrate the role of PTSD as the conduit between racial discrimination and preterm birth, Gavin said.

In the paper, Gavin and her co-authors recommend that health-care providers start screening all pregnant women for prenatal PTSD, in order to spot those at risk for preterm birth. Pursuing the role of racial discrimination, of course, requires more wide-ranging, social-justice-oriented strategies. The authors suggest greater government investment in the quantity of and access to affordable housing, and in funding for K-12 education and health care. By addressing such social factors, the authors write, the health of African-American women and their offspring can improve.

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Other authors were Nancy Grote and Taurmini Fentress of the University of Washington School of Social Work, and Kyaien Conner of the University of South Florida.

For more information, contact Gavin at gavina@uw.edu or 206-616-8847.