A new center at Duke University will be the first in the South to study the complex roles that environment, genes and socioeconomic status play in causing premature births and lower birth weights among babies born in the South.

Stephen Johnson, administrator of the U.S. Environmental Protection Agency, on Tuesday announced a $7.7 million grant to fund a five-year study aimed at reversing the recent rise in premature births and low birth weights reported in many Southern states. Both factors contribute to infant mortality, which has also started to increase in the South after years of progress in reducing it.

The grant is the largest in EPA history for a children's research center. It is the first such center in the South devoted to studying the multiple factors affecting births that are complicated by poor health.

Compared to the rest of the nation, babies born in the South are more likely to be born early and weigh too little for optimum health. Many Southern states also have infant death rates that are higher than those for the rest of the nation. And the rates vary significantly among whites and minorities.

Johnson, who appeared at Duke University's Levine Science Research Center to announce the grant, said children are sponges who absorb everything from language to learning to the environment in which they are reared.

"Children crawl on the floor, putting everything in their mouths, increasing their exposure to contaminants," he said. "By promoting children's health research, we are working to provide a healthier start for every child born in America."

The new research center will be housed at the Nicholas School of the Environment and Earth Sciences. Researchers will work with Duke doctors at the medical center.

A variety of factors

Marie Lynn Miranda, an associate research professor and director of the new center, said many potential hazards during pregnancy affect birth outcomes, including environmental exposures to substances such as mercury, lead and pesticides; social stress; a mother's health; and genetic predisposition to disease.

Miranda noted that the rate of premature births and low birth weights vary significantly by race and ethnic group.

Nationally, 18 percent of babies born to black women are premature, Miranda said. For other groups, the rates are much lower -- 12 percent for Hispanics and 11 percent for whites.

A similar disparity exists in North Carolina. Fifteen percent of black babies were born prematurely, according to North Carolina vital statistics, compared to 11 percent for whites and 8.5 percent for Hispanics. Researchers will explore these disparities and the combinations of factors that prevent and cause early births.

While not a specific focus of the research center, the infant mortality rate is linked to low birth weights and prematurity. Among minorities in North Carolina, the infant mortality rate was 14.9 deaths per 1,000 births in 2005, more than double the rate for white births. Premature births and low weight accounted for 20 percent of the deaths of infants younger than a year old, state health officials have said.

"These inequalities are especially pronounced in the American South," Miranda said. She said while the inequalities are well documented, researchers don't know what accounts for them. "It's not just a difference in income and socioeconomic status. There's more going on."

Researchers will work with community groups and local health clinics, examining how fetal growth is affected by environmental factors such as breathing polluted air and growing up in substandard housing. Miranda said premature birth can lead to obesity, heart disease and diabetes in adults.

"If we get it wrong in the beginning, there is a whole cascade of health effects that individuals grow up with," Miranda said.