Growth charts for children

The simplest way to follow a young child’s growth is to plot their weight and height over time on growth reference charts. Babies and young children who receive good nutrition and are not unwell for long periods usually have healthy patterns of growth and development. Many things influence growth, including genes, nutrition, general health and illness.

Babies and young children do not usually grow in a perfectly smooth way. They tend to grow in “bursts”, so a change in height and weight can happen over a short time. For babies, the first year of life is a period of very rapid growth.

On average, a newborn baby more than triples its birth weight by the first birthday. Growth slows in the second year, with roughly two to three kilograms added each year until the next major growth “spurt” at puberty. Doctors, nurses and other health professionals use several methods to assess growth in children.

The most common measures include:

• Basic body measurements such as weight and height (length)
• Head circumference for boys and girls from birth to about three years of age
• Body mass index (BMI), calculated for children over two years
• Child-specific BMI charts for older children

Growth charts are used to plot a child’s measurements. Your doctor or nurse can track growth from one measurement to the next and compare it against the reference range. This makes it easier to spot a developmental problem when it occurs and to act early.

How growth charts work#

Growth charts come from studies of a whole population and show the normal range of measurements for a particular group. The charts are divided into sections, called “centiles” (or percentiles), which show the proportion of the group above or below a particular measurement.

For example, a baby on the 85th centile for weight is heavier than 85 per cent of other babies of the same age and sex, but lighter than 15 per cent of them.

Although babies vary widely in size, most fall somewhere between the third and 97th centile for weight, length and head circumference.

There are a number of different charts available#

These include weight-for-age, height-for-age and head-circumference centile charts for children from birth to 36 months and from two to 20 years of age. There are also separate charts for boys and girls, whichever growth reference is used.

Some growth charts for infants are based on the growth of healthy, breastfed babies measured from birth in international studies. Whichever reference is chosen, the aim is the same: to compare a child’s measurements against a typical range for their age and sex.

Body mass index (BMI)#

BMI is one way to assess whether a child is underweight, a healthy weight or overweight. It is a single number that interprets weight in relation to height, calculated by dividing weight in kilograms by height in metres squared (BMI = weight (kg) / height (m²)).

If BMI is used for a child or adolescent, it must be compared against age- and sex-specific centile charts. This is because, as children grow, their amount of body fat changes and so does their BMI. For example, BMI usually falls during the toddler and preschool years and then rises during the school years and into adulthood.

For children over the age of two, BMI percentile charts can help assess weight and obesity. The charts use centile cut-offs as a guide only:

• A BMI above the 85th centile suggests the child is overweight.
• A BMI on the 95th centile or above suggests obesity.

Always see your doctor if you are concerned about your child’s growth#

Growth charts, including BMI percentile charts, are intended only as guides. Weight and height generally increase steadily through infancy and childhood. A change from the usual growth pattern can be a sign to seek further guidance from a doctor, child health nurse or dietitian.

Your doctor can use a range of charts and other measures to help assess whether your child is growing at the expected rate.

Key points#

• Most children grow and develop normally with good nutrition and general good health.
• Children grow in bursts rather than at a steady pace.
• Growth charts and BMI percentile charts are guides only, compared against age and sex.
• A change from a child’s usual growth pattern is a reason to seek advice.
• See your doctor if you are concerned about your child’s growth.

Where to get help#