What Are Growth Curves and How Important Are They?

These parameters are recorded on growth charts starting from the child’s birth and then at specified intervals during infancy, toddlerhood, and beyond. They essentially serve as the child’s “growth identity card,” allowing us to track their development over time.

Growth curves are created based on measurements taken from thousands of healthy children, and they can vary from one population to another. For this reason, different growth charts may be used in the UK or the United States compared to those used for the Greek population. Since summer 2017, the personal health record for children in Greece includes the growth curves from the World Health Organization (WHO).

What does it mean when we say that a child is at the 10th, 25th, 50th, 75th, or 90th percentile?

• The 50th percentile represents the average. Among 100 healthy children of the same age and sex, the child’s measurements are in the position where 49 children weigh less and another 50 weigh more.
• If a child is at the 10th percentile, it means that out of 100 healthy children of the same age and sex, 9 will weigh less and the remaining 90 will weigh more.
• Similarly, if a child is at the 90th percentile, then among 100 healthy children of the same age and sex, 89 weigh less and only the remaining 10 weigh more.

This interpretation applies similarly to other percentiles and to the growth curves for height and head circumference.

If a child’s measurements fall within the chart’s ranges and follow their curve, it is generally considered that they are growing normally. However, parents should understand that a child does not necessarily follow their growth curve perfectly. There are normal variations, such as a temporary drop in weight percentile when an infant begins eating solid foods (until they adjust) or when a child starts walking and becomes more active, potentially altering their weight trajectory.

In any case, growth curves must be evaluated by a paediatrician, who can determine what is normal and what might be pathological and require further investigation.

Katerina Katsibardi, MD, PhD
Paediatrician
Doctor of Medicine, National and Kapodistrian University of Athens
www.katsibardi.gr

Note: Regular pediatric check-ups are recommended. The article provides general information, and in any case, you should always consult your paediatrician.