African American women who report experiences of discrimination based on their race or skin color appear to have an increased risk of poor pregnancy outcomes, according to the findings of two new studies.

In one study of black and white women, researchers found that a history of perceived racial discrimination was associated with premature delivery and low-birthweight babies among blacks. In the other study, investigators found that black women who reported experiencing racial discrimination were more likely to give birth prematurely than black women who did not report racial discrimination.

Previously published reports indicate that black women are more likely than white women to experience premature delivery and to have low-birthweight babies, but the reason for the discrepancy is not fully explained by factors such as prenatal care, genetics and socioeconomic factors. Increasing evidence suggests that chronic stress from racial discrimination may play a role.

To examine this hypothesis, Dr. Sarah Mustillo, of Duke University School of Medicine, Durham, North Carolina, and her team examined information on 352 births that occurred between 1992 and 1995 among black and white women involved in a long-term study on heart disease. Their findings are published in this month’s issue of the American Journal of Public Health.

Fifty percent of the black women and 5 percent of the white women who delivered their babies prematurely said they had, at some point in their lives, experienced discrimination in at least three situations, such as at school, on the street or while getting medical care, Mustillo and her team report. The same was true of 61 percent of blacks and 0 percent of whites with low-birthweight infants.

Overall, black women were about 2.5 times more likely than white women to experience premature delivery. When the black women’s experiences of racial discrimination, were taken into consideration, however, this value decreased to 1.88 and to 1.11 after factoring in tobacco and alcohol use, education, income and depression.

“Experiences of racial discrimination were associated with preterm delivery and low birthweight, and such experiences appear to contribute to black-white differences in these outcomes,” Mustillo told Reuters Health.

She added that “racial discrimination may underlie racial/ethnic disparities in health rather than any biological notion of race.”

Dr. James W. Collins Jr., of Northwestern University, Chicago, and his team also looked at the role of racial discrimination in pregnancy outcomes in 312 African American women. These women delivered either very low birthweight infants - less than 1,500 grams (3.3 pounds) or infants weighing more than 2,500 grams.

Study participants were asked if they ever experienced racism while at work or school, or while getting medical care, getting a job, or getting served at a restaurant or store.

Those who said they had been discriminated against on the basis of their race in at least one of those areas were almost twice as likely as their peers to have a very low birthweight infant, Collins and his team report. Women who said they had been discriminated against in three or more areas were 2.6 times more likely to have a very low birthweight infant.

The association between very low birthweight infants and racial discrimination was particularly strong among women who said they had been discriminated against at work or while finding a job, study findings indicate.

“Our study suggests that a mechanism by which institutional racism affects female reproductive health is likely to be found in the reported incidents of racial discrimination in the workplace,” the researchers write.

“In conclusion,” they add, “the reported lifelong accumulated experiences of interpersonal racial discrimination by African American women constitute an independent risk factor for infant very low birthweight.”

SOURCE: American Journal of Public Health, December 2004.