Measuring growth
The Child Growth Foundation and NICE suggest children should have their growth measured at every contact with a healthcare professional.
When taking the measurements of a child living with obesity it’s important they feel comfortable. To avoid exacerbating perceptions of weight stigma, children should be taken to a private area. The Let’s talk about weight: a step-by-step guide provides useful examples of how to facilitate appropriate conversations when measuring a child. This guidance is discussed in more detail in the ‘Leading Conversations’ section.
If caregivers have concerns about how to talk about their child’s weight in a positive way or are faced with challenging scenarios, an extremely helpful resource can be found here which is also recommended to all families. This guidance is discussed in more detail in the ‘Leading Conversations’ section.
It is important to refer to local procedures and guidelines for measuring children which should be aligned with available equipment.
Mandatory and fresher training for staff involved in measuring is essential to maintain appropriate skills. The Royal College of Nursing standards for measuring growth emphasise age-based procedures and the equipment needed. This is summarised in the table below and can be accessed here.
|
Measuring height |
Measuring weight |
|
» Children aged >2 years should be measured using a stadiometer with a headboard. » The child should remove shoes, socks and hair ornaments. » The child must be positioned with their feet together and flat on the ground, heels touching the back plate, legs straight, buttocks against the backboard/wall, scapula, where possible, against the backboard/wall and arms loosely at their side. » The child’s head should be placed with the corner of the eyes horizontal to the middle of the ear. » The headboard should be placed carefully on the child’s head. » Record the height in centimetres to the last completed millimetre. |
» Children aged >2 years should wear minimal clothing and nappies and shoes and the contents of pockets must be removed. They should be weighed on sit- or stand-on scales. If clothing etc cannot be removed, this must be documented. » A child who is unable to sit or stand, or who has complex needs, should be weighed in light clothing on a hoist scale. » Weighing scales must be on a flat, hard surface and must be checked, cleaned and calibrated before use. » The child should stand centrally on the scales with their feet slightly apart. » The reading must be taken when the child is still and documented accordingly. » If a child refuses or is unable to stand still, they may be weighed in the arms of a parent, carer or healthcare professional. A child’s weight is calculated by weighing the adult and subtract this weight from their combined weight. |
Growth charts
A child’s weight and height should be calculated and interpreted, including BMI (for those over 2 years) on the age- and sex-specific UK-WHO growth charts which can be accessed here.
The Royal College of Paediatrics and Child Health provide excellent resources on how to plot a child’s growth on UK-WHO growth charts which can be accessed here.
Separate growth charts should be used where available, for example for Down's syndrome.
Definitions of BMI in children are provided by NICE as follows:
|
Definition |
BMI kg/m2 (adult criteria) |
BMI centile (child criteria) |
|
Overweight |
25-29.9 |
91st +1.34 standard deviations |
|
Obesity (very overweight) |
30-34.9 |
98th +2.05 standard deviations |
|
Severe obesity |
35-39.9 |
99.6th +2.68 standard deviations |
|
Extreme obesity |
>40 |
|
From the age of 2 years, a child with BMI ≥91st centile is classified as overweight. A child with BMI ≥98th centile is classified as obese.
The NHS BMI calculator is useful to visually demonstrate the healthy range for child growth if there is no access to BMI growth charts.
The Growth Charts UK-WHO paediatrics.co.uk app may be useful for those without access to digital growth charts on electronic patient records. This can calculate a child’s BMI and BMI centile, though it does not provide a visual output.
iGrow is a very useful electronic platform for plotting child growth for medical records.
Central adiposity
Waist circumference is a useful measure of central body fat (adiposity) which is a predictor of health risks such as type 2 diabetes. Furthermore, it provides another useful marker instead of solely focusing on weight alone.
NICE recommends measuring the waist-to-height ratio. A waist circumference that is less than half of a child’s height (a ratio of <0.5) is considered ideal.
|
Waist-to-height ratio |
Central adiposity |
Health risk |
|
0.4-0.49 |
Healthy |
None |
|
0.5-0.59 |
Increased |
Increased |
|
>0.6 |
High |
Further increased |
The ratio can be calculated as follows:
- Waist circumference: 89cm
- Height: 155cm
- Waist-to-height ratio: 89cm / 155cm = 0.57
This measurement may not be useful in all children (e.g., those at high risk of obesity) but it may be worthwhile considering children already living with obesity.
Guidance on how to measure waist circumference can be found in this online NHS England training module which is strongly recommended (see section on ‘Understanding the different levels of overweight in children and young people’).
Measuring waist circumference can be a highly sensitive matter for the individual child. It is important to request permission to perform from the caregiver and child. This should be in the context of its purpose in helping to identify a child’s health risks.