Schools have banned cupcakes, issued obesity report cards and cleared space in cafeterias for salad bars. Just last month, Michelle Obama’s campaign to end childhood obesity promised to get young people moving more and revamp school lunch, and beverage makers said they had cut the sheer number of liquid calories shipped to schools by almost 90 percent in the past five years.

But new research suggests that interventions aimed at school-aged children may be, if not too little, too late.

More and more evidence points to pivotal events very early in life — during the toddler years, infancy and even before birth, in the womb — that can set young children on an obesity trajectory that is hard to alter by the time they’re in kindergarten. The evidence is not ironclad, but it suggests that prevention efforts should start very early.

Among the findings are these:

- The chubby cherub-like baby who is growing so nicely may be growing too much for his or her own good, research suggests.

- Babies whose mothers smoked during pregnancy are at risk of becoming obese, even though the babies are usually small at birth.

- Babies who sleep less than 12 hours are at increased risk for obesity later. If they don’t sleep enough and also watch two hours or more of TV a day, they are at even greater risk.

Some early interventions are already widely practiced. Doctors recommend that overweight women lose weight before pregnancy rather than after, to cut the risk of obesity and diabetes in their children; breast-feeding is also recommended to lower the obesity risk.

But weight or diet restrictions on young children have been avoided. “It used to be kind of taboo to label a child under 5 as overweight or obese, even if the child was — the thinking was that it was too stigmatizing,” said Dr. Elsie M. Taveras of Harvard Medical School, lead author of a recent paper on racial disparities in early risk factors.

The new evidence “raises the question whether our policies during the last 10 years have been enough,” Dr. Taveras said. “That’s not to say they’ve been wrong — obviously it’s important to improve access to healthy food in schools and increase opportunities for exercise. But it might not be enough.” Much of the evidence comes from an unusual long-term Harvard study led by Dr. Matthew Gillman that has been following more than 2,000 women and babies since early in pregnancy.

Like children and teenagers, babies and toddlers have been getting fatter. One in 10 children under age 2 are overweight. The percentage of children ages 2 to 5 who are obese increased to 12.4 percent in 2006 from 5 percent in 1980. Yet most prevention programs have shied away from intervening at very young ages, partly because the school system offers an efficient way to reach large numbers of children, and partly because the rate of obese teenagers is even higher than that of younger children — 18 percent.

The Robert Wood Johnson Foundation, which helped finance Dr. Taveras’s study, is spending $500 million over 14 years to fight childhood obesity, but only in children 3 and up. And a multimillion-dollar National Institutes of Health childhood obesity project that is giving out $8 million over eight years explicitly excludes pregnant women and infants under 1.

Things are starting to change: late last year an Institute of Medicine study committee was charged for the first time with developing obesity prevention recommendations specifically for the 0-to-5 set. The report, due in about 18 months, will look at the role of sleep and early feeding patterns, as well as physical activity.

“Everybody’s been pointing to this early period and saying that it looks like something is going on and it has long-lasting effects,” said Dr. Leann L. Birch, director of Penn State’s Center for Childhood Obesity Research, who is leading the committee.

Scientists like Dr. Birch worry about what are called epigenetic changes. The genes inherited from mother and father may be turned on and off and the strength of their effects changed by environmental conditions in early development. Many doctors are concerned about women being obese and unhealthy before pregnancy because, as they point out, the womb is the baby’s first environment.

One of the most convincing studies on the link between gestational diabetes in the mother and diabetes in her children was done almost 10 years ago among Pima Indians. Siblings born after the mother developed Type 2 diabetes had a higher body mass index throughout childhood and were almost four times as likely to develop diabetes as siblings born before the diagnosis.

“The intrauterine environment of a woman with diabetes overnourishes the fetus,” said the study’s author, Dana Dabelea, an epidemiologist at the Colorado School of Public Health. And that, she added, may “reset the offspring’s satiety set point, and make them predisposed to eat more.”

Experts say change may require abandoning some cherished cultural attitudes. “The idea that a big baby is a healthy baby, and a crying baby is probably a hungry baby who should be fed, are things we really need to rethink,” Dr. Birch said.

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By RONI CARYN RABIN
Published: March 22, 2010