Stroke Risk: Could It Start In The Womb?

In both countries, there are geographic variations in stroke death that are not explained by adult lifestyle, say authors David J.P. Barker, F.R.S., of the Medical Research Council Environmental Epidemiology Unit of the University of Southampton, England, and Daniel T. Lackland, Dr.PH, professor of Epidemiology of the Medical University of South Carolina in Charleston, S.C.

There are well-recognized "stroke belts" in the United States, England and Wales. In the United States, it spans the southeastern states. In England and Wales, it's concentrated in the northern towns that expanded rapidly during the industrial revolution of the 19th century and also in poorer rural areas. Residents of these areas have unusually high rates of heart disease, stroke and high blood pressure.

"Although there is nothing today that characterizes places in England and Wales with high rates of stroke, they were characterized by poor living standards in the past," Barker explains.

Barker and Lackland analyzed data from four studies that examined the geographic distribution of stroke in England and Wales between 1968 and 1978. They compared that information with the rates of maternal and newborn deaths more than 50 years earlier, between 1911 and 1925, which was about the time the stroke patients were born.

The investigators also calculated average adult height in different parts of the country, and estimated the risk of stroke according to birth place. Short adult stature is a marker of poor growth in utero and poor living standards in childhood.

The researchers found that areas with high death rates from stroke in the 1960s and 1970s also had high maternal and newborn death rates around the turn of the century. At that time, mothers in these areas tended to be poor, malnourished and had poor health in general, including "poor physiques" marked by short stature. Their infants also had low birth weights.

One hypothesis is that coronary heart disease and stroke originate through responses to malnutrition during fetal life and infancy and that these responses permanently change the body's structure and function in ways that lead to disease in later life.

Using that hypothesis, Barker and Lackland suggest that the U.S. stroke belt is linked to a similar legacy of rural poverty. Malnutrition was common in the southeastern United States between the Civil War and the Great Depression. That, along with other socioeconomic influences impacted mothers and babies, they suggest.

Researchers also found that children born in areas with high stroke rates continue to have a high risk of stroke regardless of where they live later.

"The evidence is that the biological features of stroke originate in the world stroke patients came from rather than the world they entered when they were born," Barker says.

"A person's birthweight predicts his or her stroke risk," he says. "People who have strokes tend to have had lower birth weights."

He says protecting the growth and nutrition of young women and their babies may reduce future stroke deaths.

"It is going to take several generations for this effect to wash out," Barker says. "The lesson here is that if you prejudice the health of a girl or woman, you prejudice the health of her offspring. Stroke risk is not just in the genes. It is about the environment in the womb."

In an accompanying editorial, Larry B. Goldstein, M.D., professor of medicine at Duke University Medical Center in Durham, North Carolina, notes that this research reflects an association but not necessarily causality. However, "the data provide another compelling argument to ensure adequate prenatal care and maternal nutrition."

Goldstein, who is also chairman of the American Stroke Association advisory committee adds: "Investment in programs aimed at optimizing maternal health and nutrition may pay dividends in reducing the incidence of stroke in their unborn babies when they reach adulthood."

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Editor's note: For more information on stroke, visit the American Stroke Association Web site: http://www.strokeassociation.org.