Growth percentages, what they are and what they are for

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Philippe Gloaguen
@philippegloaguen
Author and references

Contents

  • 1 What are growth curves 
  • 2 What are the growth percentiles
  • 3 How the growth percentiles are calculated 
  • 4 Calculate the growth percentiles
  • 5 What are percentiles for 
  • 6 On what the growth of a child depends 
  • 7 Are the percentiles the same for everyone?
  • 8 Growth curve for premature babies 
  • 9 What are health balances 

Who is already a mother knows it well. The first thing we are often asked after giving birth is "how much does the baby weigh?". It almost seems like everything else is secondary to the pounds. Obviously this is not the case at all, God forbid, but it is true that weight is almost considered an infallible "indicator of well-being". In fact, if you think about it, for every mother, raising children is fundamental. And during health assessments, pediatricians also pay special attention to development, making use of two very useful tools: percentiles and growth curves. Let's see what it is and discover ours percentile calculator of growth



What are growth curves 

They are graphs that, as the name suggests, give information on the growth of a child, in particular on weight, height and head circumference. For each of these parameters there is a precise growth curve. The age of the child in months or years is indicated on the horizontal axis (abscissa) of a Cartesian plane, while on the vertical axis (ordinate) the weight expressed in kilos or the height or head circumference in centimeters. After identifying the age, you move vertically until you intersect the measure of interest. 

By combining all the points of the various measurements taken over time, the graph appears as a curve whose slope varies according to the growth of the baby, which sometimes has peaks or setbacks. Percentiles (also called centiles) are used to represent the variations of these values, which constitute a system of averages that allows us to understand if growth has a regular trend or not. 



Pediatricians usually follow safe and certified growth curves, such as those developed by the World Health Organization or the American Centers for Disease Control and Prevention (CDC). 

What are percentiles of growth

Growth percentiles can be considered a kind of unit of measurement of a child's growth. These are reference values ​​used to see how it is growing. Usually it is considered normal that which lies between the 3rd and 97th percentile. The 50th percentile represents the mean. 

We must always remember that each child is unique and, in his individuality, he is also unique in growth. Comparisons are never good, they only serve to trigger absolutely unjustified fears and anxieties. So avoid doing them, but only rely on your trusted pediatrician. 

How the growth percentiles are calculated 

To understand how growth percentiles are calculated, think of a representative sample of 1.000 children of the same age and sex. Then imagine putting all these babies in a row, weighing them and measuring them in height. After the measurements, those with similar characteristics are divided into 100 groups, each of which corresponds to a percentile. 

Let's take some examples to better clarify the concept. 

If an 18-month-old baby is at the 50th percentile weight, it means that, in his hypothetical age and sex peer group, probably half will weigh more than him and the other half less. 

If a 2-year-old girl is at the 30th percentile for height, it is conceivable that 30 girls will be shorter, while 70 will be taller. 

In growth charts, percentiles are represented by parallel curves. The central one is the 50th percentile, while below are those with the lowest percentiles and above those with the highest percentiles. If the child's growth curve runs parallel to those in the graph, it is assumed that the child is growing steadily and regularly. 



Calculate the growth percentiles

A parent can calculate their child's growth percentiles on their own, either by creating the graph by hand or by using online tools. We also offer you our calculator, in collaboration with the Bambino Gesù Pediatric Hospital. Just enter the sex, date of birth, weight and height of your puppy to get the result. The calculations are carried out on WHO (World Health Organization) data for the age 0-2 and on CDC (Center for Disesase Control) data from 2 years upwards. Do not forget, however, that only the pediatrician can give an objective opinion on the growth of the child, because he is aware of everything that concerns him (from a physical point of view) from birth. 

Enter your child's data Gender Female Male Date of birth Weight (kg) Height (cm) Service managed by Calcola {{errorMsg}} {{weightLabel}} {{clamp(p_weight, 2, 97)}}° weight percentile Weight chart Save {{heightLabel}} {{clamp(p_height, 2, 97)}}° height percentile Height graph Save The use of this tool does not replace a visit to the pediatrician: only the doctor can assess if your child's growth is progressing well and provide you with information on this. Recalculate

What are percentiles for 

Percentiles are used to get an idea of ​​a child's growth. However, being at the 4th or 95th percentile does not mean that this is poor or, on the contrary, exaggerated. It all depends on the general trend over a long period of time. A single figure doesn't say much. In other words, the really important thing is whether a baby has been constant around a certain percentile (whether low or high). 


Changes in percentiles need to be monitored. If your weight has always been at the 60th percentile and suddenly drops to the 30th percentile, you need to understand why. That is why this tool is so important for the pediatrician. The doctor has known our children since they came into the world and knows practically everything about them (what they eat, how much they sleep, what they are able to do etc.), so he is the only one who can really understand if something is wrong. and if it is necessary to investigate further with diagnostic tests. 


What does the growth of a child depend on 

We start from an assumption that should reassure us: growth is not always the same. There are times when it is faster, for example in the first three months of life or during puberty, while in others it slows down. It is absolutely physiological that this is the case and the attentive eye of a doctor is able to perceive if there could be some problem. Evaluation over time is therefore important. 

Growth does not depend only on simple "numbers", that is, on the weight, height or head circumference of the child. There are many factors that contribute to it. Nutrition, for example, plays a fundamental role at any age. The same consideration applies to sleep, measurements at birth, the week of gestation in which it was born, habits (for example, whether it goes to nursery or school) and so on. All elements evaluated by the pediatrician when he visits him. 

And then we must not forget genetics. For example, a little one who is 40th centile in weight and 60th tall is a little thinner and a little taller than the average of his peers, probably because he inherited this build from his parents. Conversely, a child with the 70th percentile of weight and the 50th of height will be a little more… fleshy. Generally speaking, children of tall or short, thin or fat couples will be more likely to be children themselves when they are adults. 

Are the percentiles the same for everyone?

Growth curves are not the same for everyone. The data you enter are always the same - weight, height and, usually up to 3 years of age, head circumference - but there are differences in other aspects. For example, the graphs (and consequently the growth percentiles as well) are different between males and females. On average, the former grow a little more than the latter and therefore it is something that must be considered when monitoring development. 

Then there are particular curves, for example for premature babies and for those with Down syndrome or some pathologies. In these cases, the growth is not the same as that of the others and must therefore be analyzed in a differentiated way. Children with Down syndrome, for example, often have feeding difficulties, with repercussions on weight. It is therefore clear that a different medical evaluation is needed. 

Growth curve for premature babies 

The growth curve of premature babies deserves a separate discussion. In this case, the "real" age of the baby must be calculated. Let's explain better. Let's take the example of a baby who is born at 34 weeks of pregnancy, which is 6 weeks before the conventional 40 weeks. At 5 months, it is very likely that his psychophysical development is that of a 3 and a half month old baby, the age he would have if he had been born at full term. Therefore, the calculations of weight, height and head circumference must be made on this age and not on the personal one, otherwise they would be wrong. 

What are health balances 

Health balances they are fixed and periodic appointments by the pediatrician aimed essentially at taking stock of how the child is growing. During these meetings, you have more time to investigate some things, compared to normal outpatient visits which mostly serve to solve a problem of the moment, such as an earache or conjunctivitis. 

In general, in the first year of life the health assessments are 5 and are made between 30 and 45 days of life, between 2 and 3 months, between 4 and 6 months, between 7 and 9 months, between 10 and 12 months (obviously depending on what your doctor decides, these "deadlines" may be different). During health checks, the pediatrician always measures the weight, height and head circumference of the children to create growth curves and check the progress of psychophysical development over time. They are also an opportunity to talk about breastfeeding, vaccines, nutrition and much more. 

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