Understanding child growth charts
What we really need to know about children’s growth charts
From the moment your baby is born their height and weight are noted and for the next few years your little one’s weight and height will be measured.
The Red Book
The Red Book is your baby’s Personal Child Health Record and your maternity unit will provide it or your midwife on their first visit.
The book includes growth charts which every time your baby is weighed and measured they’ll get a little dot on their growth chart for height, weight and head circumference. This will show you how they compare to the average baby of the same age.
How does the child growth chart work?
The growth chart looks at your child's age, weight, and height and plots them on a chart. Once your child is plotted on the chart, their plot point falls on or near a percentage line that compares your child’s numbers with those of other similar children their age.
What on earth are ‘centiles’?
In your Red Book there will be a chart is divided into centiles, which are basically just a way of comparing your baby to others. So if your baby is on the 25th centile for weight and the 50th for height, it means that if you lined up 100 babies from lightest to heaviest, yours would be number 25 (24 would be lighter and 75 would be heavier). For height, your baby would be number 50 – bang on average – with 49 shorter and 50 taller.
What do growth charts really tell us?
One thing we always know for sure is that all children are different and this is important to remember when it comes to your baby’s growth. The truth is it really doesn’t matter which centile your child is on: all the professionals are looking for is that they stay roughly around the same centile as they grow up.
So what if your child is ‘above’ or ‘below’ average?
If your child is above the 50th percentile for weight, don’t worry about it. It’s telling you that your child is proportionately above average, but this is not suggesting they are overweight. The same applies if they are below the 50th percentile doesn’t mean they are underweight.
With height, doctors generally consider genetics as an important factor, so parent and grandparent height will be taken into consideration.
What growth charts do and don’t tell us
It’s all about documenting trends. A baby starting at the bottom or top of the charts and stays in generally the same zone is not a cause for concern. But if this baby greatly climbs or falls on the charts in a short amount of time, it might signal a health condition. The number itself matters far less than regular, stable.
The relationship between the percentiles for weight and length is what really is of interest rather than the specific numbers.