Growth Charts

Overview

Growth charts can be used to monitor a child’s growth over time and involve plotting a child’s height, weight, and head circumference against expected values of children the same of the same age and sex to determine whether the child is growing appropriately.

On growth charts, height, weight, and head circumference have curves with centile labels which indicate how the child compares to the rest of the population. There are different charts for boys, girls, and preterm infants <32 weeks.

The UK WHO growth charts can be found on the Royal College of Paediatrics and Child Health (RCPCH) site.

For example, if a child’s weight is plotted and they are on the line for the 50^th centile, half of all children would be heavier or lighter.

If a child is on the 98^th centile for weight, this means they are heavier than 98% of children her age and if a child is on the 1^st centile for weight, they are lighter than 99% of children their age.

In this example chart below, plotting the child’s weight against age places the point on the 75^th centile for weight. This means he is heavier than 75% of children and 25% of children are heavier than him.

A centile space is the gap between two centile lines. A child is on a centile line if their plotted point is within ¼ of the space between the lines. If the point is further away, they are described as being between the two centiles.

Interpretation

Overview

Growth is not uniform and can fluctuate, such as if a child has an acute illness, they may lose weight and fall under a centile but generally recover to normal within 2-3 weeks.

As a summary:

• 99% of children who grow optimally fall between the 0.4^th-99.6^th centiles (the outer lines)
• 50% of children lie between the 25^th-75^th centiles
• A BMI >91^st centile suggests the child is overweight
• A BMI >98^th centile suggests the child is obese
• A BMI <2^nd centile (but not <0.4^th) is unusual and may suggest malnutrition and require further tests
• Some children require further investigation as discussed below:

The following should be investigated if any are present:

• A drop of 2 or more weight centiles
• A drop or rise through 2 or more head circumference centiles
  • Very rapid growth may suggest hydrocephalus and slowing of head circumference growth can suggest skull/brain development abnormalities
• Weight, height, or BMI below the 0.4^th centile