Physical Child growth is evident by chronological changes in — a) General body size and appearance i.e. anthropometric indicators, b) Specific features e.g. dentition and skeletal maturation, and c) Internal body composition. Despite individual variations, most of these changes follow a predictable pattern, and any significant deviation from this pattern may be the earliest or only indicator of ill health.
ANTHROPOMETRIC Child growth
Anthropometric parameters are most reliable and easily measurable indicators of somatic child growth. Some important anthropometric changes in childhood are as follows — Weight (Wt) is the most sensitive anthropometric indicator of acute child growth insults. It is essential to record Weight in each child for — a) regular child growth monitoring, b) early detection of disease and recovery, and c) calculate thug dosages.
A normal baby weighs —3.3 kg at birth and looses 10% of birth weight during first 7 days of life. Subsequently, they gain —20-30 gm/ day during first 3 months, — 400 gm/mo during 3-12 month, —2 kg/yr till 7 years and —3 kg/yr subsequently till end of puberty.
Child growth at birth: Birth Weight doubles at five months (—6.5 kg), triples at one year (—JO kg), quadruples at two years (-42 kg) and becomes seven times by 7 years (—21 kg) of age.
Weight in child growth should be measured on a electronic balance or beam balance (acceptable accuracy of 20 gms in infants and 100 gms in older children). Spring balances e.g. Bathroom scale or Salter-spring balance tend to provide false values due to loose springs after repeated use.
Length/Height in child growth (Ht) i.e. total cephalocaudal distance is termed as recumbent length up to two years of age and standing height in older children. Length/Height is a good indicator of long-term growth, as it is affected only after prolonged growth insult exceeding 3-6 month.
At birth, a term newborn measures —50 cm. Subsequently, the length increases by —4 cm/mo till 3 months (—62 cm at 3 month), than —2 cm/mo till 6 months (-.69 cm at 6 months) and than —1 cm/mo till one year (—75 cm at one year).
A child gains about half of the birth length i.e. —25 cm in first year of life (—75cm), half of the first-year gains i.e.—12.5 cm in second year (—87.5 cm), half of the second year gains i.e.—6.5 cm in third year (—94 cm) and than —5-6 cm/year till the onset of puberty.
Parental Height is an important aspect in child growth to determine height of their children’s height. Height of a boy at 2 years and girls at 2.5 years is nearly half of the adult Height (± 5 cm). It is possible to predict the adult Height in children from parental heights, using following formula — Adult Ht* (Boy) = ((Mother’s Ht +13) + Father’s Ht)/2
Adult Ht* (Girl) = { (Father’s Ht — 13) + Mother’s Ht}/2 (C predicted adult lit ± 8cm)
In child growth, Length is recorded in recumbent position, with the help of Infant-o-meter, with straight head, fully extended legs and feet at right angles to legs. Standing height is recorded in erect position without shoes, against a vertical scale or stadiometer, with heels, buttocks, shoulder and back of the head touching the scale and head in Frankfurt plane (eyes looking straight with external auditory meatus and lower border of orbit in a straight horizontal line). Length or Height should be recorded with an accuracy of 0.1 cm.
* Weech’s formula
Head circumference is the indirect indicator of brain child growth, measured by a non-stretchable plastic tape encircling Nasion anteriorly and Inion posteriorly, with an accuracy of 0.1 cm.
At birth, normal head circumference is —33 cm, increases by —2 cm/months till 3 months (— 39 cm at 3 months), —1.5 cm/months till 6 months (— 43 cm at 6 months) and —0.5 cm/months till first year (—47 cm at 1 year), —2 cm in second year (—49 cm at 2 year) and —1 cm in third year (—50 cm at 3 year).
Brain child growth is nearly complete by 3 years and further increase in head circumference is due to thickening of calvarium rather than brain growth.
Smaller head size (<31d percentile) indicates microcephaly or craniosynostosis, while larger head (>97th percentile) is seen in hydrocephalus, macrocephaly, rickets, or chondrodystrophies.
Body proportions in child growth i.e. ratio between torso and limbs may be altered in some disorders with short/tall stature. Various terms are used to denote these proportions e.g. Upper segment Vs Lower segment ratio (US:LS ratio), Crown to Rump Vs Rump to Heel ratio (CR:RH ratio) and Stem-Stature index (Sitting Ht/Standing Height X 100). Upper segment length is recorded as sitting height in child growth, while lower segment length is calculated by subtracting sitting Height from standing Height.
At birth, upper segment is longer than the lower segment, while postnatally lower segment grows more rapidly to equalize upper segment by 7-10 years.
Normal US child growth: LS ratio is 1.7:1 at birth. 1.3:1 at three years and 1 : 1 at seven years onwards. Stem-stature index is 70 at birth, 66 at six month, and 64 at one year, 61 at two years, 58 at three years, 55 at 5 years, and 52 at 7 years.
US: LS ratio is increased in short-limb dwarfism e.g. achondroplasia, cretinism and severe rickets; While it is decreased in short-trunk dwarfism e.g. spondyloepiphseal dysplasias, spinal deformities and Marfan syndrome.
Limb span in child growth i.e. the distance between tips of middle fingers of outstretched hands, is normally 1-2 cm less than Height till 10 years of age but equals or exceeds afterwards. Disproportionate increase or decrease in limb span as compared to Height indicates short-trunk or short-limb dwarfism respectively.
Chest circumference at nipple level during mid- expiration is —3 cm less than the head circumference at birth, equals at one year and exceeds afterward. Persistence of chest circumference less than head circumference beyond infancy indicates larger head e.g. hydrocephalus or smaller chest e.g. malnutrition.
Mid-arm circumference is measured at a midpoint of the hanging left arm, between the tip of acromian and olecranon processes. After initial child growth, Mid-arm circumference remains constant (—16-17 cm) between 2- 5 years of age, due to replacement of body fat with muscle mass.
A Mid-arm circumference of < 13.5 cm at any age beyond infancy indicate malnutrition – basis of various field methods for diagnosis of malnutrition e.g. Bangle test or Shakirs’ tape.
Skin-fold thickness, an indicator of body fat, is measured over the left triceps area by a Lange or Herpenden ‘s skin-fold calipers. A skin-fold thickness of <10 mm after infancy indicates malnutrition (<6 trim in severe PEM). –
Body mass index (Weight in Kg/Fit in m2) is an indicator of subcutaneous fat, the normal value being 20-25 kg/m2 during first 5 years of child growth. Calculation of BMI is more useful for diagnosis of obesity (>30 kg/m2) than malnutrition.
Body build (Somatotypes):
The term body build denotes visual physical appearance of normal children (excluding craniofacial features), which is often determined by hereditary and racial characteristics. Three main types of normal body build, as per Sheldon’s classification of child growth are —
a) Ectomorphic – Tall and linear build, with small musculature and lighter bone structure.
b) Endomorphic – Stocky-rounded build, with large amount of soft tissue.
c) Mesomorphs – Heavy muscular physique, between the ectomorphs and endomorphs.
BODY COMPOSITION
Although of little importance in assessment of child growth, it is noteworthy to remember following changes in body composition with age —
a) Decrease in total body water from —75% at birth to —60% in adults, as well as its redistribution with gradual decrease in extracellular water and increase in intracellular water.
b) Increase in skeletal muscle mass, from —25% at birth to —45% in adults.
c) Changes in adipose tissue mass in child growth, which is higher in infancy and adolescence i.e. —25%, as compared to mid-childhood i.e. —20%.
d) Changes in chemical composition of lean body mass, due to accumulation of various minerals.
e) Changes in visceral size, which usually follow the changes in body size with some exceptions e.g. postnatal regression of thymus.
