Growth assessment in children is the essential part of child health surveillance, even in absence of apparent abnormality. While assessment may be considered as one-point process, Growth monitoring is more important and requires serial data e.g. Weight, to detect changes in growth parameters over a period of time.
Indications for growth assessment in children are —
a) Routine pediatric examination*,
b) Growth promotion,
c) Identification of at-risk children,
d) Early detection of causes of growth faltering,
e) Pre-adoption assessment.
*Growth assessment in children should be done during all visit due to any cause as well as periodically monthly in first year, alternate months in second year and every three months thereafter till at least five years of age.
Methodology: growth assessment in children is a four-step process including
a) Recording of appropriate growth parameters
b) Comparing this value with reference norms.
c) Serial recording of growth assessment in children parameters on growth charts to assess growth velocity.
d) Interpretation and conveying the information to parents as well as suitable remedial action (Growth monitoring and promotion).
Step I: Selection and recording of appropriate growth parameter depends on the purpose of growth assessment in children. Although previous text has discussed multitude of anthropometric parameters for growth, only three parameters are commonly used in practice – Weight, Height and Head circumference.
Weight is the best indicator of acute growth insult, though it is of limited value for long-term growth assessment due to rapid fluctuations in health and disease. Height is a better indicator of long-term growth, as it is affected only after prolonged illnesses and remains abnormal for a long time after recovery. Recording of head circumference is essential in first 2-3 years of life as an indicator of brain growth.
Additional parameters are used in selected cases according to the purpose of growth assessment in children e.g. to assess nutritional status (mid-arm circumference, skin fold thickness), to investigate short stature (body proportions, bone age) etc.
Step II: Comparing the child’s anthropometric values with reference norms while doing growth assessment in children: Anthropometric values of the child under assessment need to be compared with corresponding values in normal children of the same age, for interpretation. These normal values are also referred as Reference norms or standards, when presented in tabular form and Reference curves or distance curves when presented in graphic form.
These norms are obtained by longitudinal or cross- sectional surveys of a large, apparently healthy population of higher socio-economic strata, to reflect maximum growth potential. In order to adjust normal variations of growth assessment in children, reference norms are established using a statistical analysis, and denoted in terms of percentiles.
If weights from a sample population for growth assessment in children of 100 children are arranged in ascending order, weight of the 50 child is most likely to be normal and reflects median value. On the other hand, children at the extremes of this arrangement are more likely to be abnormal.
Percentiles mean the location of a child’s value in this arrangement. For example, the anthropometric value of 314, 25w, 5041, 75111 or 97th child in this series is designated as 311, 25, 75th and 97’ percentile respectively.
Values between 31 and 9714 percentile cover 95% of normal children and correspond with 2 standard deviations of mean value on Gaussian distribution — a universally acceptable limit for variations. In practice, 50th percentile value is considered as ideal value, 3’ percentile as the lowest acceptable normal value and 97th percentile as highest acceptable normal value.
Thus, children with Weight or other growth assessment in children parameters below percentile or above 97th percentile are considered as potentially abnormal, while those within these limits are considered as within the normal limits of variation. However, currently available reference norms provide 5th and 95th percentile values, instead of 3 and 97th percentiles.
As the growth assessment in children is influenced by many environmental factors e.g. socioeconomic status, reference norms are also expected to be different in different populations. Reference norms for Indian children (Table 2.6A) are slightly lesser than those for western population (Table 2.6B, NCHS – 2000). For international comparison, WHO recommends the use of NCHS norms.
Step III: Serial record of growth assessment in children parameters on growth chart aims to evaluate growth velocity and identify any deviation from normal growth as early as possible, which may be the earliest indicator of ill-health. This objective is achieved by plotting the serial anthropometric values on a growth chart for comparison. Various growth charts, discussed later, are available as the simple and most effective tools to maintain these records.
Growth velocity is defined as “rate of growth or change in a growth assessment in children parameter over unit period of time”. For example, since length at birth is 50 cm and at one year is 75 cm, growth velocity in first year is 25 cm/yr.
Growth velocity is not uniform throughout the childhood and a baby has different growth velocity at different ages and for different parameters.
Growth velocity is calculated by serial recording of selected growth assessment in children parameter at different time intervals i.e. monthly or yearly and than dividing the change in parameter by the time-interval. Reference norms for different growth velocities at various age intervals are available, termed as Reference velocity norms in tabular form and Reference velocity curves in graphic form.
Step IV: Interpretation of growth records, conveying the information to parents and taking suitable remedial actions: The main objective of growth assessment in children is not only to detect the growth abnormality, but also to make mother (and family) realize its significance and take timely action. This process of continuous check and timely action is strategically described as growth assessment in children.