Thin Have-Not Tots Face Ticker Trouble
Later poverty raises risk of coronary heart disease, study says
FRIDAY, Nov. 30, 2001 (HealthDayNews) -- If you're a poor man who was a skinny baby, you're a lot more likely to have heart disease than your plumper, better-off peers, say British and Finnish researchers.
For policymakers, this means that taking better care of pregnant women and young children could improve male adult heart health, at least in response to social stresses, say the researchers. But another expert says the researchers should have considered other factors as to why men get heart disease.
Coronary heart disease (CHD), or narrowing of the arteries around the heart, affects at least 12.4 million Americans and is the leading cause of death in the United States, says the American Heart Association.
Lead study author Dr. David Barker and his colleagues spent several years studying data about Finnish men born at the Helsinki University Central Hospital between 1934 and 1944. All the men had attended child welfare clinics in Helsinki.
Barker's team classified 3,676 of the men based on their families' annual household incomes and their levels of education.
By 1971, 234 of the men had been hospitalized with CHD, while another 51 had died of the disease before admission to hospitals.
As in previous studies, the researchers found that a low birth weight and being in a poorer social class were independently linked to a higher risk of CHD.
The researchers found that growth during infancy was reduced in families in a low social class, and that poor infant growth was linked to an increased risk of CHD. They speculate that low birth weight could contribute to abnormalities in liver growth, ultimately leading to changes in fat metabolism and blood clotting.
But what most surprised Barker and his colleagues was that the risk of CHD was strongest in men who were born into low-income families and who also had lower birth weights, especially if they went on to gain weight rapidly in childhood.
Men from poorer classes who weighed less than 7.4 pounds at birth, and lower-class children who gained weight quickly during childhood had a 3.78-fold higher risk of CHD, the study says.
The findings appear in the Dec. 1 issue of the British Medical Journal.
"It now looks as though the only people who are vulnerable to poor living conditions in terms of increased risk of coronary heart disease are those people who had poor fetal growth," says Barker.
He says that begins to explain why some people in poor living conditions appear to be unaffected, while others have health problems. "Now it looks as though the ones who are vulnerable are ones who had poor growth in utero and during childhood."
Barker says one theory suggests that people living in poor conditions in Western countries must deal with psychosocial stress. "Being lower in the social hierarchy is a stress," he says.
Babies born small have altered stress responses, producing more of the stress hormone cortisol than normal, he says. "That's a life-long thing. It never goes away. They're still like that when they're 70."
The researchers say raised cortisol responses to stress caused by poorer living conditions and worsened by rapid weight gain in childhood ultimately could lead to disease.
"It says that the origins of this group of diseases -- coronary heart disease, stroke, diabetes, hypertension, osteoporosis -- lie in retarded growth before birth, which does all kinds of things to the body's structure and function. Those things are permanent for life," says Barker.
He says since a baby's birth weight is set roughly around the time of conception, the findings demonstrate the importance of ensuring the health and proper nutrition of young women and expectant mothers.
Dr. Nigel Paneth, professor of pediatrics and epidemiology at Michigan State University, in East Lansing, is somewhat skeptical about the study's methods.
Paneth says, if the data were available, looking at the mothers' backgrounds, including whether they had high blood pressure, might have been more useful. "You're saying that a low birth-weight baby has a higher risk of hypertension and heart disease later on, but because he's low birth weight, he might have had a mother who had hypertension in pregnancy."
"Birth weight is a wonderful marker of a whole set of forces," says Paneth. To take birth weight at face value by itself "can be a mistake, unless you've looked at the other forces, and I don't believe he has."
What To Do
Learn about low birth weight from the Future of Children Web site.