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Growing Pains: What Baby Growth Charts Really Mean

Growing Pains: What Baby Growth Charts Really Mean

WebMD Feature

Parents are a competitive bunch. So when the pediatrician whips out a growth chart and ranks baby's height and weight in percentiles, it's easy to wonder if something's wrong.

Tenth percentile? Something must be stunting his growth. The 95th percentile? Omigod, she's huge, so much bigger than the neighbor's little bundle. Many breast-feeding moms worry needlessly -- and even give up on the breast -- because their babies fall in the low percentiles for several months compared to bottle-fed tots. (The breast-feeders catch up later and have fewer health problems in the long run.)

But growth percentile rankings aren't meant to pit your kid against the neighbor's; they're designed to help doctors ferret out potential health or growth problems. No matter where your child fits on the chart, the important thing is that height and weight are proportional, and that growth progresses at a fairly steady pace over time.

The Yellow Springs Standard

"One mark on a growth curve means nothing," says Tampa, Fla., pediatrician F. Lane France, a spokesman for the American Academy of Pediatrics. "You're more interested in the trend. You'd like to see them at a certain percentile and then stay along the curve."

With children under 2 years, you have to take the percentile rankings with an extra grain of salt. The current standards for infant growth were published back in 1977 and based on a limited survey of babies born in Yellow Springs, Ohio, between the 1920s and mid-1970s. The babies were all white and mostly bottle-fed, so the charts don't take into account differences in growth rates between bottle and breast-fed babies or major changes in ethnicity in the United States since the '70s.

Experts believe that Hispanic kids are genetically more likely to be heavier, for example, but the current charts don't reflect this. And when Asian children are fed an American diet, they tend to grow faster than their parents, who ate a traditional diet. In general, nutritionists say, diet seems to play a bigger role than genetics when it comes to childhood growth patterns.

Don't Fall Off of the Curve

Because of those limitations, the National Center for Health Statistics is revising the growth charts based on a newer, larger survey of children of varying backgrounds. Release of the new charts reportedly hit bureaucratic snags that the NCHS won't comment on publicly. The agency says, however, that the new charts could be in pediatricians' offices by the end of 2000.

Still, the revisions are a technical change that shouldn't impact day-to-day pediatric practices or parental views of baby's progress. "The most important thing," says Jo Ann Hattner, a private nutrition consultant in Palo Alto, Calif., "is looking at your child as an individual."

This is how the growth rankings work: If a child is at the 25th percentile for her age and gender, that means that out of a group of 100 girls her age, she's bigger than 24 of them and smaller than 75 of them. Her place on the curve depends on how her genes and nutritional habits compare to the other 99 kids. "A kid can be fine at the 5th percentile for two years or at the 95th percentile," says Dr. France, and both are perfectly normal.

It's when your little one begins what health professionals call "falling off" of the curve that they take note. "If a child's been nicely growing on the 30th percentile and you see a sudden upsurge in weight, but the height is flattening out, those are red flags that should be checked out," explains Connie Evers, a Portland, Ore., child nutrition consultant.

When Baby Fat Isn't Cute

By watching the numbers, doctors may begin to suspect a chronic and metabolic illness, such as diabetes, hypothyroidism or growth hormone deficiency. Another possibility is a condition called "failure to thrive" in babies whose weight plummets out of proportion to their height.

Pediatricians are also on the look out for toddler obesity as the national battle with the bulge filters down to its youngest citizens. If your child shows a big discrepancy between your weight and height percentiles, advises Hattner, you may want to consult a registered dietician. A child under 3 years isn't likely to be put on a restrictive diet because her brain is still developing. But a dietician might suggest alterations that would help the chubby child become more height-weight proportional.

Merely being in a high percentile part of the chart doesn't mean your little one has a weight problem, however. Due to improved nutrition in the United States, babies are bigger than they were decades ago, when the infant chart data were collected. Another factor, Evers notes, is that doctors these days advise women to gain slightly more weight during pregnancy, resulting in bigger babies.

"It used to be we could predict children would end up somewhere between their mom and dad (in height)," Evers says. "Now a lot of kids are taller than mom and dad." She adds with a laugh, "My daughter's 13 and she's two inches taller than me already."

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Last Editorial Review: 1/30/2005 11:42:32 PM