Race alone does not account for higher preeclampsia rates for Black women, study finds

U.S.-born Black women are at higher risk of preeclampsia than their foreign-born counterparts, suggesting biological, cultural, and social factors may contribute to the development of the blood pressure disorder

A pregnant woman and her partner

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A novel analysis of medical records for a racially diverse group of more than 6,000 women has added to evidence that some combination of biological, social, and cultural factors—and not race alone—is likely responsible for higher rates of preeclampsia among Black women born in the United States compared with Black women who immigrated to the country.

The data on preeclampsia, a serious form of high blood pressure that can lead to deadly outcomes for mother and fetus, were gathered over a 28-year period as part of the Boston Birth Cohort study originally designed to investigate the genetic and environmental factors associated with premature births. Preeclampsia is one of the leading causes of maternal deaths worldwide, with Black women three-to-four times more likely to die from pregnancy-related causes than white women, according to the U.S. Centers for Disease Control and Prevention. Preeclampsia affects approximately 1 in 25 pregnancies in the U.S, and those who experience it have an increased risk of developing chronic hypertension and cardiovascular disease later in life.

The study was published Dec. 20 in the Journal of the American Medical Association. The new analysis, led by researchers at Johns Hopkins Medicine, specifically examined differences in hypertension and other cardiovascular disease risk factors and prevalence of preeclampsia among Hispanic, Black, and white women. Results showed that all three groups of women who gave birth and were born in the U.S. had a higher cardiovascular disease risk profile than foreign-born counterparts after accounting for differences in weight, smoking, alcohol use, stress, and diabetes.

For Black women, birth status outside the U.S. and shorter duration of residence (those who lived in America for less than 10 years) were associated with 26% lower odds of preeclampsia. Birthplace status and duration of U.S. residence was not significantly associated with the odds of preeclampsia among Hispanic and white mothers who were born outside the U.S.

Overall, the researchers said, the findings suggest that disparities related to place of birth, or "nativity," in preeclampsia among Black women are "not fully explained" by nativity differences in sociodemographic or cardiovascular disease factors.

"Immigrants come here to seek a better life, but what we are seeing is unhealthy acculturation and assimilation," according to lead researcher Garima Sharma, director of cardio-obstetrics at the Johns Hopkins University School of Medicine.

"Some women come here healthier and they get unhealthier over time probably by adopting habits of the dominant culture that increase poor health outcomes. While we didn't specifically look at the impact of structural racism on health in this study, it may also play a role here. Black women who were born outside the U.S. but immigrated to the country recently may be somewhat protected from the effects of discrimination because they tend to settle in immigrant-concentrated residential areas with increased social support," Sharma added.

Sharma emphasized that further research is needed to explore the interplay of biological and psychosocial and social determinants of health contributing to pregnancy-related disparities in preeclampsia. For years, it's been said that being a Black woman is a risk factor for preeclampsia, said Sharma, but "we need to move beyond putting all the implications on a particular race without accounting for why that is, because in this study, it's clear that Black women born outside the U.S. are less likely to have preeclampsia until they have been here for some time."