September 08, 2004
Dr. Harvey Karp, a renowned expert on children’s health and associate professor of pediatrics at UCLA School of Medicine, explains the children’s growth chart and what parents should watch for.
What are growth charts, and when are they used?
In medicine we always are comparing. That’s how we notice, “Wow, that doesn’t look normal.” Whenever a doctor measures something (including when he asks if your child is walking yet) he checks to see if it is in the general range of normal.
Growth charts are an amazing way of showing the height of thousands of healthy children on a single piece of paper. When you look at the normal weight for a 2-year-old, you are actually looking at the weight of several hundred normal, healthy 2-year-olds all averaged together, so you can see the entire range of normal. Like Goldilocks, we check to see if a baby weighs too much, too little, or just right. (The thinnest 5 percent are considered outside the norm as are the heaviest 5 percent.)
A child’s growth should be measured and plotted on a growth chart every visit to the doctor. That’s how important it is! Like measuring temperature or blood pressure, measuring height and weight gives important information that a child is healthy or not.
When should a parent worry? If a child is below the 5th percentile or above the 95th percentile, is that a problem?
Not necessarily. Some kids are just naturally petite or naturally big. Don’t panic over your child’s percentile. More important than the percentile is:
1) What’s normal for YOUR family? (How big is your family and how do they grow?)
2) How is your child growing over time?
3) Are height and weight in proportion?
In many families there are slow bloomers or kids who were super stringbeans as little kids or people with really big heads. So, if they are otherwise healthy and “following the curve,” there is no cause for alarm.
A child who is gaining weight too slowly and "falling off" the growth curve or, conversely, gaining weight too fast and zooming across the lines, has to be watched carefully and is a possible red flag.
"Following the curve" means that a child's rate of growth is normal. In other words, they are staying at about the same percentile at each visit. (One exception to this is between 6 months and 2 years, when many babies slow down their weight as they switch from a baby's normal rich diet full of breast milk or formula to a less caloric diet of table food.)
When height and weight are in balance, a child's body is proportional. If a child is at the 10th percentile for height but 75th percentile for weight, that child has a weight problem, even though her weight is well within the normal range for other kids her age.
Can you predict a child's adult height from the growth chart?
In general, kids who are growing steadily at a certain height percentile stay there, but there are lots of exceptions. I was one of the shortest kids in my class until 10th grade. Now, I'm 5 foot 11 inches. An accurate prediction of a child's height requires mixing together their growth rate plus their parents' history of puberty. Early puberty shuts off growing early on and late puberty allows kids to grow a couple of more inches.