Frequently asked questions about your child's growth measurements

Scroll through the different questions below for more information and support, or alternatively click on one of the links to be taken to a specific section.

• What are child BMI centiles?
• How will my child be measured?
• At which stages will my child be measured?

What are child BMI centiles?

A child’s BMI tells us if their weight is in proportion for their height. Instead of using the BMI categories used for adults, a child’s BMI is given as a centile (or percentile). Due to children constantly growing until around the age of 18, their biological sex and their age is also used to work out their BMI centile. A small change in weight or a few months difference in age can change the centile score.

The BMI calculator works out if a child or young person is:

• underweight: on the 2nd centile or below
• healthy weight: between the 2nd and 91st centiles
• overweight: 91st centile or above
• very overweight: 98th centile or above

The BMI calculator is in line with the measurements found within the National Child Measurement programme (NCMP) link to NCMP page. For more information you can see the Royal College of Paediatrics and Child Health (RCPCH) national growth charts .

Your child’s centile charts can be found in your personal child health record (the red book). Examples of child growth charts can be found here.

If you’re concerned about your child’s weight, contact your GP or health professional.

How will my child be measured?

A health professional will use the following tools to measure your child:

• Scales

• Length mat

• Height Chart

• Head measurement tape

Your health professional will then document growth measurements in your child’s red book and their electronic health records.

Your child’s red book explains that babies come in all shapes and sizes, and they do not all gain weight at the same rate, so every chart will look different when its filled in.

When a health professional monitors your child’s growth, it may go up and down on the centile chart. If this happens, the health professional will need to review and discuss this with you.

At which stages will my child be measured?

Growth reviews are important in understanding how your child is growing and developing. Growth measurements start from the moment you find out you’re expecting a baby, whilst you’re pregnant they are completed by a midwife. When your child is born, their growth will be monitored by your health visiting team.

Your health visiting team will measure your child at the following stages:

New birth visit

Weight measurement will be completed.

6-8 weeks

Weight and head circumference measurement will be completed. Your child’s length may be measured at this stage if required.

10-12 months

Weight measurement will be completed.

2 and half years

Weight and height are measured at this stage.

Additional contacts may be required to monitor the growth and development of your child.

If you’re concerned about your child’s development at any time, please contact your GP or health visiting team.