The growth curve is a very important tool that will allow you to control the height and weight of your child from birth, to follow his progress and thus, his health. Different curves will accompany the start of his life depending on his age. What are they and how do they work? Let's do a check in !
Even before birth, the fetus is measured during ultrasound scans to monitor that its development is taking place normally. The same goes for the baby once it comes into the world. From his life as an infant to that of a teenager, or even a young adult, your child will grow, put on weight and these data will make it possible to establish a single curve whose evolution will indicate whether his growth is in the average and if he is. in good health. On the contrary, abnormalities such as too low a weight or too small a height can indicate problems or illnesses and may serve as a wake-up call.
This growth will be calculated from the child's weight, height, cranial perimeter (head circumference) and body mass index (BMI). Depending on their age, the measurements should be taken at different intervals and then the data entered in the child's health record, in a table reserved for a specific section. Several curves will thus serve as a reference and they are different for girls and for boys.
Baby's early years are crucial for their physical (and mental) development and their growth should be closely monitored. According to Inserm, the ideal follow-up consists in measuring and weighing the child "every 3 months up to 1 year, every 6 months until the age of 4, then every year" until the end of his puberty. However, the medical follow-up of the baby established in France includes 4 close examinations during the first 2 months, then 7 between 3 and 18 months. During these visits, it is systematically measured and weighed.
What do growth charts look like?
In total, we find in the health record, between pages 78 and 87, 10 different growth curves:
- Girls' weight curves 1 month – 3 years
- Boys' weight curves 1 month – 3 years
- Girls' waist curves 1 month – 3 years
- Size curves boys 1 month – 3 years
- Cranial perimeter curves girls 1 month – 5 years
- Head circumference curves boys 1 month – 5 years
- BMI curves girls 1 month – 18 years
- BMI curves boys 1 month – 18 years
- Height and Weight curves girls 1 month – 18 years old
- Height and Weight curves boys 1 month – 18 years
Because head circumference growth and height growth are not quite the same in girls and boys, each gender has its own set of curves.
These curves are present on a grid allowing the measurements to be pointed out and the child's own curve to be drawn using these data. They are divided into several lanes corresponding to the different routes observed on average to establish these references.
The cranial perimeter curve
It fits your baby's head circumference and is used to monitor the growth of his brain, which is very fast. During its first months of life outside the womb, this organ completes its formation by taking advantage of the fontanelles, these membranous and malleable structures that are not yet ossified to adjust to the new size that the brain will make. With it, your child's entire nervous system is also developing. It is therefore particularly important to be able to detect an anomaly as early as possible.
The measurement of the baby's head circumference is carried out using a flexible meter by the doctor or pediatrician and, since April 1, 2018, now takes into account the parents' head circumference in order to match the growth standard to that of the inherited genetic heritage.
What does an inferior cranial perimeter curve mean?
A head circumference lower than the reference curve indicates microcephaly, a rare congenital malformation that is thought to affect between 2 to 12 viable newborns in 10,000 (studies conducted in the United States). This growth failure may have started as early as pregnancy and, in this case, can be detected by ultrasound, or it can begin from birth.
If not related to a genetic defect, microcephaly may have been caused by the mother's exposure to infections, such as cytomegalovirus (CMV), toxoplasmosis or rubella, to harmful substances (drugs, alcohol, toxic chemicals) but also to severe malnutrition or the Zika virus. It can also occur after a delivery in which the baby has been deprived of oxygen, or from a postnatal infection of the infant, such as bacterial meningitis.
What does an upper head circumference curve mean?
If the cranial perimeter is greater than the reference curve, it is called macrocephaly. More common than microcephaly, it can be hereditary and appear as early as the development of the fetus or appear after birth.
The enlargement of the skull can be caused by hydrocephalus, which is a buildup of cerebrospinal fluid (CSF), or by a subdural hematoma caused by meningitis or trauma. In these cases, surgery will remove the blood or fluid.
The waist curve
The child's growth in stature is extremely rapid in the early years. On average, between birth and 4 years old, her height will double, going from around 50 cm to 1 meter! It is therefore essential to follow it in order to spot an anomaly, either by a lower or upper curve, or by a break in the curve indicating sudden acceleration or delay. The size of the parents is also taken into account in the interpretation of data because it can explain a possible remarkable deviation from the reference corridors. "80% of healthy children will have a final height between this parental target size – 6 cm and + 6 cm", recalls INSERM.
A lower curve indicates stunted growth, the origin of which can be varied. It can indicate a nutritional problem in the child, a bone disorder or a hormonal deficit and reveal the first symptoms of certain diseases (rickets, hypothyroidism, etc.).
When unrelated to genetic makeup, a larger waistline is rarer and often indicates a hormonal problem that can be treated with hormone therapy to slow growth.
The weight curve
Just as he grows quickly, the child also gains weight quickly in the first year. Then, he must take it regularly to ensure good growth. The weight curve thus makes it easy to spot stagnation in newborns as well as any other peaks and disturbances during childhood.
If the child's weight is below the lower curves, it is called weight loss. The causes can be various but the most common is insufficient nutrition. In the baby, it can be the consequence either of too difficult breastfeeding or of too diluted preparations, or by digestive disorders of the baby. In older children, it can reflect a bone development disorder, chronic disease, food allergies or anorexia.
Conversely, when the curve is greater, we will speak of overweight. If the increase in weight is confirmed significantly with each measurement, it may be an early sign of obesity. However, the weight curve alone is not sufficient to identify the problem. For this, its interpretation must be made in parallel with that of the size. This is why the health record now includes a build curve.
The BMI (Body Mass Index) curve
To calculate the child's BMI, the doctor applies the weight / height² formula. This index is calculated at the same time as the infant's measurements are entered, then at least once a year from the age of 2 years. The BMI curve, for both girls and boys, has 3 periods. The first corresponds to the baby's first year during which he grows and gains weight a lot. This growth slows down markedly afterwards, when he begins to walk, and the BMI decreases. It gradually resumes around the age of 5, during what is called the "adiposity rebound". In some children, this episode may appear early and be a sign of onset of obesity. By spotting it so early, it is possible to act before the overweight sets in and becomes much more difficult to treat.
If the BMI curve is lower and above all shows a break, the child is in a worrying situation of thinness which can be caused by undernutrition, eating disorders (which themselves can be caused by mental or emotional disorders) , digestive disorders or chronic disease. In infants, it can also be a sign of hypotrophy, an insufficient development which can, moreover, be detected during pregnancy during ultrasound. Here again, early identification can allow rapid and effective treatment.
In the health record, the body mass index curve is put in parallel with the child's height / weight curve, which takes into account the pubertal stage but also the target height. This target height is the average height of the father and mother, plus 13 cm for boys and minus 13 cm for girls.
The importance of the harmony of curves
For both girls and boys, in the case of height and weight, a slightly lower or higher curve does not necessarily mean that the child's growth is abnormal. The important thing is that this growth is harmonious and that the evolution of the curve is constant. The real sources of concern and signs of anomalies are stagnation, peaks and falls in the curves.
Updated curves
Did you know ? The growth charts in health diaries have recently undergone a major update. In fact, until 2018, the curves used were those proposed by the WHO in 1979 and were based on measurements of children born in the 1950s. It goes without saying that things have changed since then. at the level of morphologies but also at the level of calculation methods. To update these data, more than 5,000,000 measurements on 216,000 children aged 0 to 18 have been carried out throughout France by researchers from INSERM 1153 / CRESS (Center for Epidemiology and Statistics Sorbonne Paris Cité) as well as paediatricians and general practitioners.
These new measurements have therefore made it possible to establish new curves in the health record, taking into account other parameters such as the size of the mother and that of the father and their cranial perimeters, but also more growth corridors, the addition of corpulence by the BMI, as well as a distinction between girls and boys in the evolution of weight and height for the period from 0 to 3 years.
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