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23 November, 2009

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Growth - assessing babies to preschoolers

A young child’s growth can be measured in a variety of ways. Most babies and young children who receive good nutrition and are not sick for long periods will have normal growth and development patterns.

Many things influence growth including genes, nutrition, good health and sickness. Babies and young children do not usually grow in a perfectly smooth way. They usually grow in ‘bursts’. A change in height and weight can occur in a short amount of time.

For babies, the first year of life is a time when they grow very rapidly. On average, a 3.2kg baby will end its first year at around 10kg, more than triple its birth weight. Growth slows down in the second year with, on average, two to three kilos added each year until the next major growth ‘spurt’ at puberty.

How growth is measured
Doctors, nurses and other health professionals use a variety of ways to assess growth in children. The most common ways include:

Basic body measurements including weight, height (length) and head circumference for male and female children from birth to three years of age
Standards called growth references or growth charts that are used to help interpret these measurements
Calculation of BMI (body mass index) and child-specific BMI charts for older children.

Growth charts in Australia
Growth charts are used to measure children’s growth. Your doctor or nurse can track your child’s growth from one check-up to the next and also compare it to the national average. This makes it easier to identify a developmental problem when it occurs and take early action.

Growth charts are taken from studies of the population as a whole and reflect the normal range of measurements for a particular group (for example, all babies born in a particular year). The charts are divided into sections, called ‘percentiles’, which show the proportion of the group that is above or below a particular measurement. For example, a baby who is on the 85th percentile for weight is heavier than 85 per cent of other babies in Australia (of the same age and gender) but weighs less than 15 per cent of other babies. Although babies may be very different in size, the majority are somewhere between the 5th and 97th percentile for weight, length and head circumference.

In 2005 Victoria adopted a recommendation of the National Health and Medical Research Council to use the United States Centre for Disease Control growth charts to assess and monitor the growth of children. There are a number of different charts available. These include weight-for-age, height-for-age and head circumference percentile charts for children aged from birth to 36 months and two to 20 years of age. There are separate charts for boys and girls.

Body mass index (BMI) for children
The body mass index, or BMI, is one way to assess whether a person is underweight, normal weight or overweight. The BMI is a single number that interprets a person’s weight in relation to their height. It is calculated by dividing a person’s weight in kilos by their height in metres squared.

BMI = Weight (kg)
Height (m²)

If a BMI calculation is used for a child (or for an adolescent), it must be compared against age and gender percentile charts. This is because, as children grow, their amount of body fat changes and so will their BMI. For example, BMI usually goes down during the preschool years and then increases into adulthood.

For children over the age of two, BMI percentile charts can be used to assess weight and obesity. The charts use percentile cut-offs as a guide only. Weight above the 85^th percentile and below the 95^th percentile suggests the child is overweight. The 95th percentile and above indicates obesity.

International growth charts for fully breastfed infants
In April 2006, the World Health Organization released new growth charts for infants and children aged up to five years. Unlike current growth charts, the new charts are based exclusively on breastfed infants from healthy populations.

Growth charts are only guides
Growth charts for children, including the BMI percentile charts, are intended only as guides. They can indicate when to make small changes and when to seek further guidance from a doctor, maternal and child health nurse or dietitian.

See your doctor if you are concerned
Always see your doctor if you are concerned about your child’s growth. Your doctor can use a range of charts and other measures to help assess whether or not your child is growing at the expected rate.

Where to get help

Your doctor
Maternal and Child Health nurse
An Accredited Practising Dietitian, contact the Dietitians Association of Australia
Maternal and Child Health Line Tel. 13 22 29
Nurse-on-call Tel. 1300 60 60 24
Go for your life Infoline service Tel. 1300 73 98 99
Primary School Nursing Program, Office for Children and Early Childhood Development Tel. (03) 9096 8653
The Royal Children’s Hospital Tel. (03) 9345 5522

Things to remember

Most babies and young children will grow and develop normally if they receive good nutrition and are not sick for a long time.
Growth charts for children, including the BMI percentile charts, are intended only as guides.
Always see your doctor if you are concerned about your child’s growth.

You might also be interested in:
Child development (1) - newborn to three months.
Child development (2) - three to six months.
Child development (3) - six to nine months.
Child development (4) - nine to 12 months.
Child development (5) - one to two years.
Child development (6) - two to three years.
Child development (7) - three to four years.
Growth - assessing primary school children.
Growth - assessing teenagers.

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