Black Infant Deaths Tied to Birth Weight
Black infants born to college-educated parents have higher death rates than white infants born to similar parents, according to a new study by the U.S. Centers for Disease Control.
The difference was attributed to a higher percentage of low birth weight babies born to black parents. Black and white infants of normal birth weight in the study had equivalent death rates.
The study, reported today in the New England Journal of Medicine, is an important advance toward understanding why black babies in the United States are more than twice as likely as white babies to die by age 1.
But it leaves unresolved the question of why college-educated blacks are more likely to give birth to low birth weight babies than their white counterparts. The vast majority of such babies are born prematurely.
“There is an excess rate of low birth weight (among blacks) even at higher socioeconomic status which remains unexplained,” said one of the study’s authors, Dr. Diane Rowley of the Centers for Disease Control. “We probably need to focus research efforts to look specifically at the very low birth weight group.”
The researchers suggest myriad possible explanations, ranging from poor maternal health before pregnancy to inadequate prenatal care to stress and discrimination that might trigger physiological changes leading to premature births.
Some researchers have postulated an intergenerational effect, in which a mother’s birth weight and early childhood development may be reflected in her children’s birth weights.
As scientists search for definitive answers, Rowley and her colleagues emphasized the early initiation of prenatal care as “the best available method of preventing premature birth.”
In an editorial for the New England Journal about the study, two Harvard Medical School physicians argued that the stress related to racism might play a role.
Drs. Paul H. Wise and DeWayne M. Pursley wrote that the factors studied by epidemiologists, such as income and education, might mean different things for blacks than for whites. Such simple terms may not reflect, for example, “the treatment of black professionals mistakenly taken into police custody or the experience of a black family firebombed out of a previously all-white neighborhood even though they can afford their mortgage payments more easily than their white neighbors.”
In 1989, the infant mortality rate for blacks was 18.6 per 1,000 live births, compared with a rate of 8.1 per 1,000 live births for whites, according to federal data.
The higher percentage of premature and low birth weight babies among blacks is crucial in explaining these statistics. Independent of race, very low birth weight babies--those under 3.3 pounds--are about 90 times more likely to die by age 1 than normal birth weight babies, according to Rowley. The infant death rate of low birth weight babies--born at between 3.3 pounds and 5.5 pounds--is seven times higher than normal birth weight babies.
The researchers analyzed data from the National Center for Health Statistics covering 865,128 white infants and 42,230 black infants born between 1983 and 1985. All of the children were born to college-educated mothers and fathers. In these groups, the infant mortality rate was 10.2 per 1,000 live births for black infants, and 5.4 per 1,000 live births for white infants, suggesting that a higher parental educational level corresponds to an overall lower infant death rate in both groups.
The actual death rates for low birth weight babies were slightly lower for blacks than for whites. But about 7% of the black infants had low birth weights compared with about 3% of the white infants.
This higher percentage of low birth weight babies explained the overall racial disparity in infant death rates, the report said. If low birth weight babies had been excluded, the death rates for black and white infants would have been equal.
The study found that black or white babies of normal weight with college-educated parents have an equal chance of surviving the first year of life. But in the general population, black infants of normal birth weight have almost twice the infant mortality rate of comparable white babies.
In addition, black babies and white babies from families with college-educated parents have comparable rates of the sudden infant death syndrome as well as preventable mortality.
