05/07/2012 04:22 pm ET

Most Moms Wrong About Babies' Body Size

When it comes to truly seeing their toddlers, many moms fall short. That's according to new research that finds 70 percent of moms inaccurately gauge their baby's body size, a misperception that may have profound implications for a child's health down the road.

"Both parental perceptions of body size and how satisfied parents are with that body size" affects the diets that parents choose for their children, "since perceptions are likely to guide behavior," said Erin Hager, an assistant professor in the Pediatrics, Growth and Nutrition division at the University of Maryland School of Medicine.

To gauge parental perceptions, Hager and her co-investigators gave 281 low-income moms, many of whom were themselves overweight, a drawing of seven toddlers who ranged from underweight to obese. The moms were asked, "Which picture looks most like your child?"

Only 30 percent of moms successfully picked a drawing that accurately represented their baby's body size, while 70 percent of the moms were off in assessing their toddler's weight.

Inaccuracy was highest among overweight toddlers' moms, who were 87 percent less likely than mothers of healthy weight toddlers to be accurate. However, mothers of underweight children were nine times more likely to be right.

The researchers also looked at how pleased moms were with their kid's weight, concluding that overall, satisfaction was fairly high.

More than 70 percent of all the moms surveyed were pleased with their child's body size. And among moms whose kids were overweight, that figure was even higher: nearly 82 percent of moms with overweight toddlers were pleased with their children's weight.

"High-weight status is often regarded as a sign of successful parenting, especially during the early years when parents are responsible for their child's health, nutrition and activity opportunities," the authors write in the new study, published inThe Archives of Pediatric Adolescent Medicine Monday.

"It's hard to tell why," Hager added. "We looked at mothers' body size, thinking obese moms would be more inaccurate, but we didn't find a strong predictor."

"It's probably more of a cultural issue," she continued. "As a culture, we believe chubby toddlers and babies are healthy. Also, there are so many overweight children in the U.S., an overweight body type has become the new norm."

A growing number of studies have found that when it comes to body-weight perception, people often get it wrong. A recent study in the journal Body Image, which looked at Mexican college applicants, found that only 63 percent accurately reported their weight. Approximately 1 in 3 young men in that study were overweight, but less than 17 percent of them identified as such.

In an editorial accompanying the new Archives study, Dr. Eliana Perrin of the University of North Carolina at Chapel Hill School of Medicine, argued that the findings matter deeply, because having an accurate sense of a child's weight influences parents' readiness to make weight-related behavioral challenges. In other words, misperceptions can be a barrier to achieving and maintaining a healthy weight.

The situation is complicated by the fact that with so many overweight and obese children, the understanding of what "normal" means has changed, Perrin states.

"The old way of explaining the child at the 85th percentile -- 'If you gathered 100 children, he would be heavier than 85 of them' -- no longer rings true to parents," she writes.

Dr. Christine Chiaviello, a pediatrician with the Long Island City office of Tribeca Pediatrics, said she was not at all surprised by the findings, but questioned whether the drawings used by researchers might not explain why so many moms got it wrong. Incremental differences between the seven drawings were sometimes subtle, which may account for some mothers' inaccuracy. Researchers only counted a response as inaccurate when moms were off by two or more steps on the chart, however.

"Sometimes, we can't tell just by looking at children whether they're underweight or overweight. The obvious ones are pretty obvious, but that's why we have growth curves, because you just can't tell," Chiaviello said. Indeed, pediatric growth charts tracking children's height and weight to provide a general picture of size and health have been used since the late 1970s.

But even with such evidence before them, Chiaviello said, many parents still find it challenging to face up to any weight issues their young children are facing.

"Often, I'll be making good eye contact [with the parents] on everything and I'll say, 'Let’s look at growth curve,' and all of a sudden, they're looking past you," Chiavello said. "It's a very, very difficult issue."

Seventeen percent of children ages 2 to 19 are now considered obese, which not only puts them at greater risk of being obese as adults, but also increases the likelihood that their obesity will be severe.