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Baby fat may seem cute and cuddly, but new research is finding that rapid weight gain in infants could be an early predictor of obesity.

With nearly a third of all Canadian children considered overweight, public health advocates have long tried to target this group to find ways to cut those rates, including revamping school cafeteria menus, encouraging more outdoor play and banning full-calorie pop from vending machines.

But new research suggests those interventions may be targeting the wrong age group.

With excessive weight gain and even obesity rates rising in preschoolers and toddlers, health experts are wondering if action should instead be focused on children's earliest years -- or perhaps even before they are born.

It's well-known that excessive weight gain during pregnancy is not safe for the mothers-to-be, since it can lead to gestational diabetes, difficulty losing weight after the pregnancy and even the development of type 2 diabetes later on.

But little attention has been given to what effect a mother's excess weight has on the baby inside her.

Dr. Glenn Berall, the chief of pediatrics at North York General Hospital in Toronto, says that evidence is now starting to emerge – and it's not good.

"There is evidence that the environment in the womb makes a difference, so that mothers who are higher weight during pregnancy have greater likelihood of a baby who ends up obese later in childhood," he told CTV's Canada AM earlier this week.

"If they have too much weight gain in pregnancy, that's a risk factor [for the baby developing obesity later in childhood]. You can even track it back to the mother's pre-pregnancy weight as well."

He says an obesity campaign need to be working on teaching women how to end up with a reasonable weight after their pregnancy even before they get pregnant.

"If we can get to the moms before they even get pregnant – when they are just thinking about it, there is a lower risk of childhood obesity," he says.

Obesity campaigns also need to focus on infants, particularly with evidence that rates of overweight are rising in this age group.

A huge study led by researchers at Harvard Medical School in 2006 that looked at more than 120,000 babies born between 1980 and 2001 found the prevalence of overweight infants younger than six months old ballooned 74 per cent during that time period.

"The obesity epidemic has spared no age group," the study's lead author, Matthew Gillman, an associate professor at Harvard Medical School, said at the time of the study's release.

"These results show that efforts to prevent obesity must start even before birth."

Another analysis that came out of the same study, published last year in the journal Pediatrics, found that rapid weight gain during the first six months of life may place a child at risk for obesity by age three.

Dr. Berall says research has also found that children who are obese at age three have a strong likelihood of spending the rest of their lives battling their weight.

Children who are overweight in their preschool years are more likely to be obese in childhood. And children who are overweight during their school years have a high likelihood of being overweight into adulthood, he says.

Another study released earlier this month, again in Pediatrics, concluded that the factors that place children at higher risk for obesity begin at infancy, and in some cases, during pregnancy.

"This early life period -- prenatal, infancy, to age five -- is a key period for childhood obesity prevention, especially for minority children," says Elsie Taveras, lead author of the study and an assistant professor of population medicine and of pediatrics at Harvard Medical School.

To stop the cycle, Berall and other experts say the key is taking measures to slow weight gain in babies and toddlers who are putting on weight too fast.

Berall says that will take a shift in cultural thinking, since we tend to think of a chubby baby as a healthy baby who will "grow into his or her weight" -- not one who needs to go on a diet.

"Our society has a bias toward higher weight in infants. You hear comments like ‘That baby is cute and cuddly,' or ‘That baby has a healthy appetite.' But that sometimes means that baby may be eating too much," he says.

Experts are now starting to believe that a baby's first year is a critical time for setting the stage for obesity, though it's unclear why. It could be that is the time when a baby's brain adapts to wanting excessive food. Or it could be that too much food taxes an infant's developing pancreas, and therefore the body's response to insulin, and lays the groundwork for obesity.

Or it could be that behavioural patterns are set early that continue into childhood and beyond. Taveras' research, for example, found that the most important risk factors for childhood obesity included poor feeding practices, insufficient sleep, and televisions in bedrooms.

She said it's often assumed that these and other risk factors are caused by low income and low educational levels. But she says when she and her team adjusted for socioeconomic status, they found that the prevalence of many of the risk factors remained the same.

Taveras says it's more likely that the risk factors stem from behaviours and habits passed from on generation to the next, or ones that are culturally embedded.

"For a lot of patients I see in my clinic, it's intergenerational — for example, the grandmother in the home is influencing how her daughter feeds her own child," she said.

That's especially true when it comes to at what age mothers begin giving their infants solid food or when the mothers decide to stop breastfeeding, Taveras says. Research suggests that starting a baby too early on solid food increases their chances of gaining weight too quickly, paving the pay for weight problems to begin.

Berrall says babies young children are often encouraged to eat more than they want to, or to finish a bottle of formula, rather than let it thrown down the sink. But it's those kinds of feeding habits that set a child up for eating problems, he suggests.

Berall says children naturally know when they're full and will signal that by turning their head from the spoon or bottle or breast when they're full. Caregivers need to recognize and listen to those signs, he says.

"The No. 1 advice we can give to parents is let the kids determine their appetite. People worry about finishing what's on their plate. Let me them set their appetite and their fullness signals will work," he says.