From the first time that your infant sees the pediatrician, there’ll be a growth chart in the medical file and it will stay with that file until adulthood. The chart, an example shown above, was developed by the Centers for Disease Control to display weight and height data for your child in comparison to other children of the same age. It shows the information graphically on a percentile basis so that the medical staff can gain a quick understanding of where Junior in relation to all the other kids of his particular age.
Why Does the Chart Matter?
It’s certainly helpful to know where Junior is relation to the rest of the boys his age. Should you start thinking of a basketball scholarship or is that not too likely? Apart from that, your child’s growth rate is a possible indicator of whether there might be lurking difficulties. For example, if he’s been persistently in the 85th percentile for height but suddenly drops to the 35th percentile around his eighth birthday, the doctor might consider whether there are other health issues at play. That’s not necessarily the case, but it is a consideration.
It can also indicate whether Junior is getting off his diet and thus affecting his weight. There are significant risks associated with poor diet, principal of which is Diabetes.
On a more practical level, it’s helpful when buying clothes to know whether he runs shorter or taller than the typical boy of his size. If he’s in the 95th percentile for height, then you should look a size upwards.
How Do I Read the Chart?
The sample chart is for boys from two to twenty years of age and shows the age in years on both upper and lower horizontal axes. The left and right vertical axes list stature (height) and weight in both the English and Metric systems. There are two range-bound curves, upper and lower. The upper range pertains to the child’s height for the 18 year duration and is bounded at the 5th percentile and the 95th percentile. The lower range pertains to the child’s weight and is also bounded at the 5th and 95th percentile. Remember that the percentile is a measure of about where he is in relation to any 100 randomly chosen boys of his age. The 50th percentile means that he’s smack dab in the middle while the 90th percentile shows that he’s bigger than 89 of the 100 boys.
The nurse or physician will measure your child at each physical and then mark the appropriate height and weight on the chart. For example, Junior is in for his pre-kindergarten physical at the age of five. His height is 3’5" (41") and his weight is 44 lbs. He might seem perfectly proportional given the closeness of the numbers, but entries on the chart at the fifth year mark would reveal that he’s at roughly the 15th percentile for height but the 75th percentile for weight. Clearly, he’s built like a fireplug – for what that’s worth.
You can download a copy of a chart for both your baby and child, split out by the gender, from the Centers for Disease Control website.