Accurate measurement of height, length, weight, head and chest circumference is a vital part in the overall assessment of the infant and child in order to assure health and identify nutritional status and the impact of disease on the child. Measurements of at least two parameters are required in order to accurately assess growth. This information must then be plotted on to the relevant growth charts for the child’s age and sex before it can be interpreted.

Every infant and child should have their growth assessed when accessing a health care provision.

Weight is measured with an age-appropriate scale: an electronic digital platform scale for an infant. This should measure weight to the nearest 10 g for a child. Depending on their condition, a standing or sitting scale that will measure to the nearest 100 g should be used for an older child.

Accuracy in weighing the infant and child and the documentation of that weight are important as their medication and fluid requirement will be calculated on that weight.

The scale must be calibrated in accordance with the hospital policy and the manufacturer’s instructions.

Infants should be weighed naked, toddlers in their undergarments and children in their outdoor clothing with heavy items and shoes removed. Parental involvement is key at this point to reassure the child and to keep them calm and co-operative. A warm, private area is required for undertaking this procedure.

If child is wearing a prosthetic device or other medical device that cannot be removed, this needs to be noted when documenting the weight.

• Place infant on scale and remain close at hand. Place your hand lightly above their body.
  
• Distract the infant and note reading when the infant stops moving.
  
• Record the weight to the nearest 10 g.
  
• If repeated measurements are required, it is important to weigh at the same time every day.
  
• Document the weight on the percentile chart and in the care records.
  
• Clean scale in accordance with hospital policy and manufacturer’s instructions.
  
• Replace paper sheet.

• Ask the child to stand still on weighing scale. It may be necessary to provide a distraction technique.
  
• Child may be weighed standing or on sitting scales.
  
• Note weight to nearest 100 g.
  
• Document the weight on the percentile chart and in the care records.

The body mass index (BMI) is used in the assessment of growth in contemporary practice as the prevalence of obesity in childhood is increasing. It is considered to be an accurate determinant in quantifying obesity, and the BMI is categorized as normal, overweight, obese or morbidly obese.

Body mass index is determined by the calculation of weight in kilogrammes/height in metres².