Height and growth: What's normal and what's not

When you look at any group of people - kids or adults - you'll see a bunch of differently sized humans. Some are taller, some are shorter, some are fatter and others are slimmer.

With so many different shapes and sizes, how can we - and doctors - know if our kids are growing normally? What are potential signs or problems with the way our children are growing? And when should we be worried about height and growth?

What is normal growth?

Your child's growth is tracked on a development chart from the moment he is born. Measurements of his length, weight and head circumference are taken in the first minutes of life and these measurements are then put onto his own development chart to begin mapping his growth and development.

Doctors have been tracking the growth of children over many years and growth charts have been developed to reflect the information that has been gathered. Growth charts are used to compare the growth of children of the same age and gender as well as to follow the pattern of your child's height and weight growth over time.

Growth charts use percentile bands to plot your child's growth. These percentile bands cover the variations of 'normal' growth - and most children consistently fall somewhere between the 5th and 97th percentile bands which are all normal. If your child is in the 40th percentile for weight and length, it means that he is heavier and taller than 40% of other kids of the same age and sex. A child in the 80th percentile for weight or length is heavier or taller than 80% of other kids of the same age and sex - both children, though, fall comfortably within the 'normal' range.

Having a child high or low in the percentile bands doesn't indicate that he is more or less healthy than other children. Consistent growth along any percentile band shows 'normal' growth and may indicate nothing more than the fact that your child may be on the shorter - or taller - side of average.

What do growth charts show?

Mostly, growth charts show consistent growth from baby to older child, but in some cases, they can be used to detect development problems. For example, if your child is growing disproportionately - height and weight percentiles becoming vastly different - a growth chart will swiftly pick up on this and clearly highlight the growth pattern changes on the chart for further review.

What affects your child's height?

While genes play a huge part in predetermining how tall your child will be (eg short parents usually have short children) other factors have an impact on how much your child grows. These include:

• Gender
• Nutrition
• Hormones
• Physical activity
• Environment
• General health

You can work out how tall your child is going to be by using a height predictor tool:

Height Predictor

A quick and easy tool for predicting your child's height.
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Growth charts for children over 24 months

With regular visits to your baby health clinic, your child will be regularly weighed and measured and that information plotted on his growth chart. But as these visits tend to taper off after 2-3 years, this regular measuring also becomes more infrequent and many parents become unsure about whether their child is continuing to follow their own normal growth patterns.

Growth charts for children 2-18 years (when the vast majority of young adults have finished growing) are available, and you can continue to plot your child's development along these charts yourself. Obviously, if you are concerned at any time, you should see your GP to discuss the matter.

Australian and New Zealand growth charts

• Girls aged 2 - 18 years
• Boys aged 2 - 18 years

Please note: Different countries have different growth charts based on data that is relevant to that population so it is important to use Australian growth charts to avoid giving yourself unnecessary worries. You can find out more information about this using the World Health Organisation child health standards.

General growth guidelines

Generally, height and weight develop along the following guidelines:

Height:

• 0-12 months - grows approximately 25 cm
• 1-2 years - grows approximately 13 cm
• 2-3 years - grows approximately 9 cm a year. Most kids will have doubled their birth height by the time they are 4 years old.
• 3 years - puberty - grows about 5cm a year. Puberty will cause periods of rapid growth (growth spurts) that are individual to each child.

Weight:

• 2 weeks - regains birth weight and then gains 0.7 - 0.9 kg a month
• 3 months - gains about 500g a month
• 5 months - has doubled birth weight
• 1 year - has tripled birth weight and gains about 200g a month
• 2 years - has quadrupled birth weight and gains between 1.8 - 2.3 kg a year
• 9-10 years - begins to gain weight faster due to the onset of puberty - approximately 4.5kg a year.

When should I be worried?

Because there is such a wide range of growth and development that is considered within normal range, mostly there is nothing to worry about. Occasionally, though, growth chart patterns can signal a health problem.

Sharp change in percentile band pattern

If your child's growth has been consistently following the 80th percentile and suddenly drops to the 40th percentile, this could indicate that there may be a growth problem and warrants further investigation by a specialist.

Your child's weight and height percentiles aren't moving in the same trajectory.

Most children's weight and height develop along similar lines - if they aren't in the same percentile, they will still move forward at the same rate. If, however, your child's weight and height are developing at different rates, this could indicate that there is a problem and should be discussed with your doctor.

Your child falls outside the percentile bands completely

Almost all kids fall somewhere between 5th and 97th percentile bands on the growth chart. If your child falls outside these parameters (more commonly, he is smaller rather than taller than normal), this may indicate that there is a health problem and should be discussed with your doctor.

This article was written by Ella Walsh for Kidspot, Australia's best family health resource. Sources include WHO and The University of NSW.