Most, if not all, pediatricians use WHO growth charts to monitor a child's growth. One in particular, the baby height percentile, has become quite popular among parents that you can find calculators and charts littered all over the Internet. Unfortunately, not all parents know how to correctly read the results of these charts. Because of our experience with scores, we automatically think that a higher value is better than a lower one, especially when it concerns percentiles. In the case of any type of growth chart, however, the “score” isn't nearly as important as the pattern.
Before going into detail on how to use the baby height percentile, it is important for parents to know how it came about. This WHO growth chart, along with the others, was constructed by studying thousands of children living across the globe in an environment that is optimal for growth. The data was then collated into graphs according to the children's age and gender. The average baby height of these children was marked as the 50th percentile. This means that half of the kids in the group would be taller than the average and half of them would be shorter than the average.
Now, most baby height percentile calculators will automatically plot a child's measurement once a parent inputs it. But charting the data on the graph yourself isn't that hard to learn. Looking at the chart, you'll see the bottom of the chart will show the baby's age while the right-hand side will show the measurement. To find out your baby's percentile, simply look for the point where his age and his height intersect on the graph. There will be times that your child's “point” will not fall directly on any curve on the chart. Instead, it may fall between curves such as falling in between the curve for the 75th percentile and the 90th percentile, maybe somewhere between the 80th to 85th percentile.
When interpreting the results shown on the baby height percentile chart, or any other WHO growth chart, it is important to remember that there is really no good or bad “score.” Being on the 90th percentile doesn't mean that a baby is healthier or is growing better than 90% of babies who are similar in age and gender. It only means that your baby is taller than 90% of kids his age and shorter than 10% of those kids. It is also important to know that the objective of these charts is not to focus on any single point. Everyone comes in all shapes and sizes. What you'll need to focus on is the pattern of growth that the child shows over time. A steady growth curve is more important than being on the higher percentiles of any WHO chart because it indicates a normal growth. Drastic and repeated changes in his growth pattern, on the other hand, may indicate problems that will need to be further evaluated.
It's very important that parents know how to use a baby height percentile chart and to interpret its results. Knowing can save parents from feeling panic and worry over their baby's health. It will also prevent parents from feeling like they're failing their child in some way, as has often been the case when it comes to these charts. And when it comes to your baby and you, knowing the correct information always matters.