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Growth Monitor

How we calculate growth


Children grow at different rates at different ages and along different tracks. The GrowthMonitor app uses 3 different measurements to accurately assess your child’s growth:

1. It compares the child’s height measurement with children of the same age and sex

Growth charts allow us to understand whether a measurement is normal by comparing it with the normal range of measurements for other children of the same age and sex. 

The percentile number shows how a child’s height compares to children of the same age and sex. The middle of the ‘normal’ range is the 50% percentile. For example, if your child is on the 75th percentile for height, they are taller than 75% of children of the same age and sex and 25% of children are taller than him/her. The 10th percentile means 10% of children of the same age and sex are shorter or 90% of children are taller.

When you first use the app to measure your child’s height, GrowthMonitor will automatically plot the measured height on the correct growth chart so you can see where your child lies compared to other children of the same age and gender.

The GrowthMonitor technology can detect whether the measured height is within or outside the normal range. If it is outside the normal range for age and sex it could be above (taller) than expected or below (shorter) than expected. The app will detect both and will let you know if your child’s height looks normal. Importantly, it will send an ‘alert’ if something does not look quite right.

Many factors determine a child’s height including their diet, health and the environment in which they live. However, it is estimated that about 80% of a person’s height is inherited from their parents. Consequently, the ‘target’ or expected height of a child can be predicted from the biological parents’ heights. 

2. Comparing the child’s height measurement to parent’s heights

GrowthMonitor can compare the child's height measurement to their parent’s heights and see whether it matches the genetic or ‘target’ expectation.  The more accurate the entered parent’s heights are, the better the app is at estimating this.

If only one parent’s height is known, you can still enter this, and it will calculate the estimated target height based on only one parent. If both parents’ measurements are not known, the app will still calculate the other measurements.

3. It monitors the child’s growth over time

Although children grow at different rates at different ages and along different tracks, most children will follow a centile on the appropriate growth charts. To properly monitor a child’s growth, it is important to see the change over time. This can only be assessed if several measurements are taken, usually 6 months apart. 

GrowthMonitor will prompt you to take measurements at 6-month time points to assess whether the change in growth is as expected. There is no limit to how many measurements you can take with the app but if you get an amber alert, you will not get repeat alerts if you take measurements less than 4 months apart. This is because it is important to see how your child is growing over a reasonable length of time. 


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