By
msnbc.com contributor
updated 9/8/2009 8:50:43 AM ET 2009-09-08T12:50:43

Obese women who manage to shed excess pounds before becoming pregnant may be able to break the cycle of inherited weight problems and pass along better health to their children, a new study shows.

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Researchers found that children were less likely to become obese if their mothers lost significant weight through obesity surgery before becoming pregnant, according to an upcoming study in the Journal of Clinical Endocrinology & Metabolism. The children with the surgically slimmed mothers also looked to have a lower risk of heart disease and diabetes.

“We’ve shown that when the mother loses weight prior to becoming pregnant, the kid does not become obese,” said Dr. John Kral, study co-author and a professor of surgery and medicine at the State University of New York Downstate Medical Center in Brooklyn.

Other studies have shown that obese moms are more likely than slim women to have obese children, Kral said.

And the health risks associated with obesity are well-documented for both moms and babies, said Dr. Dominic Marchiano, an assistant professor of obstetrics and gynecology at Pennsylvania Hospital in Philadelphia.

But until now, it was unclear exactly how to break the cycle.

Steeped in sugary womb
The new results shift some of the blame for childhood obesity from genes and the home environment to the conditions a fetus encounters as it matures in the womb.

Factors in the uterus might affect how a kid’s genes function later on, Kral said. For example, obese mothers often have blood sugar levels that are too high.

“And that can leave the kid marinating in sugar as he develops,” Kral said “But it’s not only that. There are many other substances in the amniotic fluid of an obese woman that can affect the developing offspring.”

Kral and his colleagues studied 111 children from Quebec City, some of whom were conceived before and some after their moms had weight-loss surgery. The kids ranged in age from 2 to 26.

The 49 moms in the study had a procedure called biliopancreatic diversion, or BPD.

That surgery directs food to bypass part of the small intestine and also makes the stomach a little smaller. The resulting weight loss is mainly due to the fact that people absorb fewer calories, Kral said, adding that studies have shown that people with BPD continue to eat significantly more than people who are naturally lean. This suggests that what the moms ate later on, during their babies’ childhoods, wasn’t the difference; instead, it was likely their actual weight loss.

The women in the study had lost an average of 36 percent of their body weight and had kept the weight off for about 12 years. They also had experienced improvement in their cholesterol and blood sugar levels.

Kral and his colleagues counseled the women to hold off on conceiving until they had achieved their desired body weight. When the women did become pregnant, they were given supplements to make sure that their babies didn’t miss any important nutrients, Kral said.

Healthier babies
When the researchers compared children conceived before and after a mom’s weight loss surgery, they found startling results: post-surgery babies were smaller, though not underweight, and they were three times less likely to become severely obese as they grew up.

The children born to thinner moms also appeared to be healthier overall, with lower insulin resistance and cholesterol levels, signs of a reduced risk of diabetes and heart disease.

And these results were the same when the researchers limited their analysis to children who were siblings: 25 of the 49 moms had children born both before and after their surgeries.

What was most striking, Kral said, was that you could break a family’s cycle of obesity by getting the mom to lose weight. 

Further, Kral said, it really doesn’t matter how the moms drop the pounds. The results are expected to be the same if a mom loses weight through dieting instead of surgery.

These new results may give those contemplating pregnancy another incentive to slim down, Marchiano said. “We always recommend that women lose weight prior to conception — but not while they are pregnant,” he added. “This may help with motivation as women think about the weight destiny of their children.”

Linda Carroll is a health and science writer living in New Jersey. Her work has appeared in The New York Times, Newsday, Health magazine and SmartMoney.

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