October 22, 1997 University of Illinois at Chicago Contact:
Danny Chun (312) 996-2269 [email protected]

NOTE: STORY IS EMBARGOED UNTIL 5 P.M. EASTERN TIME, WED., OCT. 22

Two Chicago researchers have published new findings that challenge the genetic concept of race as it relates to birth weight. Writing in this week's New England Journal of Medicine, they reported that black women born in the United States -- whose genetic makeup is about three-fourths African and one-fourth European -- have infants weighing, on the average, 12 ounces less than infants of white women born in the United States. In contrast, black women who immigrated from West African countries have babies whose average birth weight is less than four ounces below white infants.

The researchers, Dr. Richard David, a neonatologist at Cook County Hospital and associate professor of pediatrics at the University of Illinois at Chicago College of Medicine, and Dr. James Collins, a neonatologist at Children's Memorial Hospital and assistant professor of pediatrics at Northwestern University Medical School, analyzed more than 90,000 birth certificates of infants born in Illinois between 1980 and 1995. The study involved more than three thousand births to African women, mostly immigrants from Nigeria and Ghana, and is by far the largest analysis to date that specifically looked at the outcomes of infants born to women immigrating from sub-Saharan Africa to the United States.

Other medical researchers have theorized that racial differences in birth weight are genetic. Such a theory would predict that women born in Africa -- whose genes are by definition all African -- should have the smallest babies.

"We have found the opposite," says David. "Regardless of socioeconomic status, the infants of black women born in Africa weighed more than the infants of comparable black women born in the United States."

Their study also found that the incidence of low birth weight (weight less than five pounds) was 13.2 percent among infants of U.S.-born black women, 7.1 percent among infants of African-born black women and 4.3 percent among infants of U.S.-born white women. Among the women at lowest risk (those 20 to 39 years old, with 12 years of education for themselves and their spouses, early prenatal care and no previous prenatal loss), the rate of low birth weight in infants of African-born black women (3.6 percent) was closer to the rate of infants of U.S.-born white women (2.4 percent), while the rate in infants of U.S.-born black women remained high (7.5 percent).

David and Collins suggest that future research on black-white differences in birth outcomes should target social causes, including lifelong exposure to racial discrimination.

"Birth weight is important because small babies are more likely to die, David said. "To say race differences in birth weight are genetic is to justify thousands of excess black infant deaths each year as if this were an unavoidable fact of nature. The excess low birth weight among African Americans -- and the excess deaths that come with it -- are caused by a social system, not by genetics."

David and Collins also note that the vital records they analyzed in their study contain minimal clinical information. "Data on cigarette smoking, weight before pregnancy, and weight gain during pregnancy might, if known, have explained some of our findings," says David.

In an accompanying editorial, Dr. Henry Foster Jr. of Meharry Medical College comments that "the study by David and Collins is an important addition to the evidence that many behavioral, social, and economic questions need to be answered before a genetic cause is assumed for the differences in birth weight between blacks and whites."

-UIC-

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