In many parts of the Southeast, strokes are twice as common as in the rest of the country. Regional differences in diet, exercise and lifestyle don't explain the disparity, and for decades scientists have been mystified by the so-called "Stroke Belt."
Epidemiologist Daniel Lackland thinks he's found at least part of the explanation. And it goes back to the womb.
Combing through health statistics, Lackland found that the high-stroke areas also have increased rates of low-birthweight babies. Many of those infants were found to be at greater risk of having a stroke later in life.
The link may seem random, but Lackland, a professor at the Medical University of South Carolina, says the data are clear: "There is a very good association between low birthweight and stroke."
His work is part of what some researchers call a brewing revolution in our understanding of chronic disease. Scientists are finding more and more evidence that what happens to a fetus in the womb can determine health risks decades later.
The theory is known as "fetal programming" because these early alterations seem to set a person's cellular code for life. Proponents say it could change the way we think about and treat common ailments such as heart disease, cancer and obesity.
"Clearly, what happens in utero sets the susceptibility for lots of disease," says Georgetown University cancer researcher Leena Hilakivi-Clarke, who is studying the connections between fetal programming and breast cancer.
For decades, scientists agreed that most chronic illness was caused by a combination of lifestyle factors - such as diet, exercise and stress - and genetic makeup.
But now, some researchers have focused on a third factor: how the body assembles itself during its 40 weeks in utero. Acting on signals from the mother's body, the fetus seems to permanently alter its development in ways that can profoundly influence future health.
The theory was first developed two decades ago by University of Southampton epidemiologist David Barker. While studying heart disease rates in England, he realized that low-birthweight babies were much more likely to suffer from cardiovascular illness as adults.
"Chronic heart disease is primarily determined by the failure of the mother to deliver nutrients to the fetus," says Barker. He has come to think that fetal programming also plays a central role in many other chronic ailments.
Long-term effects
