MD probes link between birth weight, teen obesity Pregnant women eating too much, Ottawa doctor fears

Tom Spears
The Ottawa Citizen

August 23, 2004

Ottawa doctor Shi-Wu Wen is heading to China to see whether the biggest babies become overweight teens -- a theory that could challenge the heavy diet often prescribed for pregnant women in Canada.

Dr. Wen will have access to years of data charting the growth of 30,000 children in a well-to-do suburb of Shanghai. As the economy there prospers, women are having heavier babies than before.

The children in his study were all born between 1993 and 1995, as the good times in the community grew.

And thanks to scrupulous medical record-keeping in that region, the doctors noticed that newborn babies started getting heavier.

In 1993, 4.4 per cent of the babies were in the heavyweight category of four kilograms (8.8 pounds) or more -- big by Chinese standards. (The Society of Obstetricians and Gynecologists of Canada uses the same definition of a big baby.)

The following year, 4.8 per cent of the babies were in this group. And by 1995, 5.7 per cent of the babies were in the heavy group.

The diet of Chinese people in wealthy regions like Shanghai, an international trading city, is shifting away from high-fibre, low-fat foods to Western-style foods with more energy that the body can store as fat, Dr. Wen says.

Suddenly, the locals are putting on weight.

His working theory is that the babies who are born heavy will become obese as adolescents.

And he believes that we in Canada are pushing mothers to gorge on too much food in the groundless fear that babies-to-be need all that nutrition.

The Chinese doctors have kept records on the 30,000 children that include at least 11 physical exams at which height and weight were recorded -- a statistical gold mine for the gradual changes in their growing bodies.

These children are now aged nine to 11.

Dr. Wen is an epidemiologist -- a doctor who studies patterns of health or illness in a population -- at the Ottawa Health Research Institute.

He will team up with a Chinese researcher to do physical exams of the children and follow their health and their weight for a number of years, looking for patterns to emerge.

Scientists call this a "cohort study." The work is funded by the Canadian Diabetes Association, which is alarmed by the growing number of obese teens who are developing Type 2 diabetes -- a disease once seen mostly in adults.

When pregnant woman gain too much weight, the cause could either be too much food or the wrong kind of food, "and we think the wrong kind of food is the most likely answer" in the Shanghai area, Dr. Wen said.

If so, this may have profound meaning for pregnant woman in Canada.

Health Canada recommends that women of average body mass gain 25 to 35 pounds in pregnancy.

"We think the (nutrition) guideline in Canada is too liberal," and encourages mothers to overeat, Dr. Wen said. "We used to discourage a woman from eating too much, but that was 10 or 20 years ago. Now we encourage women to eat too much. ... The hypothesis is that if she doesn't eat enough food, the baby does not get enough nutrition."

Yet most underweight babies in Canada, where food is plentiful, probably owe their low weight to other causes, he believes. These include mothers who smoke and disorders in the placenta that stop nutrition from passing from the mother.

copyright The Ottawa Citizen

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