Stature
At birth
...........
50 cm
One year
50% more
75 cm
At four years old
Doubled
100 cm
12 years old
Tripled
150 cm
Weight
At birth
............
3.4 kg
At 4-5 months
doubled
6.8 kg
One year
Tripled
10 kg
At 6 years old
Sixfold
20 kg
12 years old
Doubled
40 kg
Growth is regulated by numerous factors internal to the body (such as thyroid hormones and GH) and external (such as nutrition, physical activity and socio-economic habits).
The pathological manifestations of growth are often the expression of alterations of the endocrine glands (in particular adrenal, thyroid, pancreas and pituitary).
This ratio, equal to about 1.7 in the newborn, falls to just below the unit when growth is complete
GROWTH OF BODY SYSTEMS: occurs in different ways and rhythms based on the body system considered; some, such as the musculoskeletal, respiratory and digestive systems, follow the growth curves of weight and height, while others - such as the nervous, lymphatic and reproductive systems - follow a rhythm of their own. A particular case is represented by the thymus, which begins to atrophy in coincidence with the pubertal spurt (see figure).
The monitoring of body growth processes (auxological evaluation) represents an optimal indicator for assessing the health of the child. To correctly interpret the data collected during the various stages of growth, it is necessary to compare them with reference standards, obtained from the average of a large child population homogeneous for sex and age.
Since growth presents a great individual variability in the times and measures with which it occurs, normal limits have been set by dividing the range of data collected into 100 parts, called percentiles. This division was performed so that a defined proportion of the sample children were above and below particular measurements at particular ages.
The 50th percentile represents the average growth values, while another curve, corresponding for example to the 30th percentile, informs us that a certain percentage of children have lower values (in this case 30%), which become higher in a "equally determined population (in this case 70%). We could therefore compare the growth percentiles to binary normality.
The reference limits of the healthy population are included between the lower and upper curves, which represent, respectively, the 3rd (97% of children record higher values) and the 97th percentile (97% of children record values lower). More specifically, most of the authors interpret the data collected by referring them to the following ranges:
overt pathology; with reference to stature, a height less than the 3rd percentile (dwarfism) is not necessarily pathological; for this reason a thorough specialist visit is required (assessment of bone age, growth rate, blood chemistry tests, etc.); the same goes for stature above the 97th percentile.
As anticipated, the growth curves vary according to the measured characteristic (height, weight, head circumference, etc.), age and sex. In the first two years, for example, it is preferred to measure the length in the supine position, while from this age onwards we proceed with the normal measurement of the standing height.
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