ROANOKE TIMES
Copyright (c) 1997, Roanoke Times
DATE: Sunday, February 2, 1997 TAG: 9702030118
SECTION: NATIONAL/INTERNATIONAL PAGE: A-7 EDITION: METRO
SOURCE: Associated Press
Is our weight our fate?
Does our size at birth foreshadow our risk of suffering the most common miseries of old age - illnesses such as heart disease, strokes, high blood pressure, even some kinds of cancer?
Odd as it sounds, this idea is gaining momentum among those who study the origins of disease. The theory has taken shape over the past 10 years, but its foundation was laid in England at the start of the century.
In 1905, when the inspector of midwives in Hertfordshire recruited nurses to help women in childbirth, part of the job was writing down the infants' sizes. Eventually, all the ledgers listing names and weights ended up in archives, where they sat, forgotten, until the 1980s.
For those who look at patterns of health on a large scale, the books were a treasure. Here were the birth sizes of thousands of men and women now in their 50s, 60s and 70s. The next step was obvious: See if there was a link between these people's weights at birth and their health as adults.
A team from the University of Southampton tracked down 15,726 people born between 1911 and 1930. They focused on those in the normal birth range between 5 1/2 and 9 1/2 pounds. It turned out that the more they weighed at birth, the less heart disease they had.
And that's not all. As the researchers dug deeper, they found that bigger newborns also are more likely to avoid strokes, diabetes, high blood pressure and potbellies when they grow up.
``The destiny of newborns is, to an extent, already determined,'' said Dr. David Barker, who pioneered the field.
While certainly not entirely fate, these scientists believe birth weight does influence what people eventually die from.
Over the past decade, Barker's group worked largely alone. They went over health records in England and India and published more than 50 reports and two books on the connections between babies' weights and shapes and their health in later life.
In recent times, others have gotten involved, including some who set out to disprove the theory. But in the end, they have turned up even more reasons to think birth weight truly does matter.
One of the biggest surprises to emerge from the latest research is the discovery that being extra-large at birth is not always a good thing. Big babies, it seems, are more likely to have breast or prostate cancer in old age.
None of this seems to apply to babies who are small because they are premature or twins. But for full-term newborns, the research suggests that being on the small side is best for avoiding cancer and being big is best for most everything else.
But what - if any - practical lessons should be taken from these discoveries remains unclear. Doctors know little about how to influence birth weight, and even less about what the ideal should be. Instead, many believe the real significance of these discoveries is the clues they offer about the inborn sources of human illnesses.
Even though several new studies have confirmed Barker's findings, including two big ones at Harvard - the Nurses Health Study and the Health Professionals Follow-up Study - some still have doubts.
Especially troubling to the doubters is their difficulty understanding how birth weight could matter so much.
``One of the reasons researchers are skeptical about Barker's hypothesis is that the specific biological explanations are not always very satisfying,'' said Dr. Allen Wilcox of the National Institute of Environmental Health Sciences.
Satisfying or not, Barker strives to build believable scenarios about what could be going on inside the womb.
In his view, the rapidly growing fetus is constantly adjusting to the supply of nutrients it receives from its mother. If it gets too little, it will slow the growth of some organs to spare others that are more important, especially the brain.
Just which organs are affected depends on when in gestation the deprivation occurs.
In this way, the theory goes, glitches in the flow of nutrition may permanently change the structure of the heart, liver, kidneys, blood vessels and more. But the impact might not be seen until middle age or beyond.
Babies who have big heads relative to the rest of their bodies appear more likely to have high cholesterol levels when they get older, Barker said.
He believes they were undernourished late in gestation and diverted blood away from their trunks to their brains. One of the organs that suffered was the liver, which processes cholesterol.
Barker also speculates that babies who are small but otherwise proportionate are more likely to have high blood pressure as adults because disrupted nutrition somehow interferes with construction of the arteries, making them less elastic.
Of course, all the ills of adulthood cannot be blamed on life in the uterus. Adult habits still count. But Barker contends that a bad start before birth may make some unhealthy conditions of adulthood even more dangerous.
Other researchers are groping to explain why being born extra-large might increase the risk of some kinds of cancer.
Dr. Anders Ekbom and others from Upsulla University in Sweden found that the largest baby boys appear to have twice the risk of prostate cancer as the smallest ones when they reach adulthood.
At Harvard, the Nurses Health Study found a similar increase in the adult risk of breast cancer for the largest baby girls.
Maternal hormones, as well as nutrition, influence fetal growth. Some researchers speculate that high exposure in the womb to growth-promoting estrogen and other hormones could increase the risk of these cancers.
Or maybe it's simply a matter of size. Bigger baby girls grow up, generally, to have larger breasts. And the more breast tissue a woman has, the greater her chance of cancer.
Even if some of these theories about birth weight turn out to be true, they are unlikely to lead to recommendations to manipulate birth weight anytime soon.
First, trying to produce bigger or smaller babies is impractical - even if doctors knew the ideal size. The most powerful influence on fetal growth is smoking, which reduces the baby's size by about a half-pound. The mother's diet is important, too, but hearty eating is no guarantee of a hefty baby, and poor nutrition doesn't necessarily produce a small one.
Furthermore, even among those who believe birth weight counts, researchers argue over just how much.
``It is very important to emphasize that the vast majority of people who have hypertension had normal birth weights,'' said Dr. Gary Curhan of Harvard. ``It isn't the explanation for all heart disease or diabetes. It is one piece of the puzzle.''
In the end, birth weight may turn out to be one more bit of useful medical history, such as knowing that heart attacks run in the family.
LENGTH: Long : 125 lines ILLUSTRATION: PHOTO: AP/File. Karin Michels, an epidemiologist at Harvardby CNBSchool of Public Health, said that "apparently, many chronic
diseases have their origins much earlier in life than we would have
thought."