Height and weight percentiles in boys and girls: What are they and how to interpret them?

The height and weight of children are one of the health indicators that parents are most concerned about. It is currently known that they are subject to multiple factors, from family genetics and mother’s diet during pregnancy to breastfeeding and infant diet, which means that both weight and height can vary from one child to another depending on their living conditions. However, regardless of these variations, experts recognize that there is an adequate average of child weight and height for each age and sex: the percentile.

What are height and weight percentiles?

Basically, height and weight percentiles represent the weight and height values ​​for each age , according to sex. These are reference values ​​used by health professionals to assess the growth rate of children, from birth to around 8 years of age, when child development normalizes.

Thanks to these values ​​it is possible to determine if children are gaining weight at an adequate rate, below or above the optimal rate and thus prevent disorders such as malnutrition and childhood obesity. They also allow knowing if children are growing properly, at a rate lower or higher than the average for their age, and thus correct alterations such as growth retardation.

Growth patterns WHO Child

WHO girl weight-for-age percentilesPercentiles of weight-for-age boy WHO Height/height percentiles for age WHO girlPercentiles of height / height for the WHO child age

How to read the height and weight percentiles?

Read the height and weight percentiles is actually not that complicated when you know what each axis and line means. In this type of table, the horizontal axis usually represents the child’s age while the vertical axis graphs the weight or height. The intersection of these axes in the center of the table represents the percentile, represented by a line, which follows a staggered order from number 3 to 97.

To read For a child’s height or weight percentile, find their age on the horizontal axis and find their corresponding weight or height on the vertical axis. Once the age and weight or height have been identified, a line is drawn from each axis until they coincide in the center of the table with one of the percentile lines. This will be the child’s height or weight percentile.

How to interpret height and weight percentiles?

The percentile number obtained reflects the child’s weight or height compared to other boys or girls of the same age. For example, if a child has a height percentile of 90, it means that compared to 100 other children of the same age, 90 will measure less than him and 10 more. On the other hand, if a child has a weight percentile of 10, it means that, compared to 100 other children of his age, 90 will weigh more than him and 10 less.

In general terms , a percentile around 50 means that the size or weight of a child is average compared to the rest of their peers. On the other hand, a percentile below 50 means that your weight or height is below average and if the percentile exceeds 50 it indicates that you are growing above average.

However, it is worth clarifying that having a low or high percentile is not synonymous with a developmental alteration since all percentile lines are considered statistically normal. Only children who exceed the percentile 97 because they are too tall or too overweight or below the 3rd percentile because they are too short or thin will require further analysis.

In any case, it is important to note that the value of the percentile alone does not determine a child’s health status. In order to know if a child grows in a healthy way, it is essential that the percentiles of height and weight are balanced with each other, a criterion that refers to the Body Mass Index, and that said percentiles do not suffer great variations during the first years of life. life.