The growth charts in your child’s ‘Red Book’ (Personal Child Health Record) show a graph of the normal distribution of the heights, weights and also head circumferences of healthy children. Understanding their use is key to monitoring your child’s growth patterns.
Growth charts are based on measurements collected from thousands of children, across several countries and ethnicities. There are separate charts for boys and girls, as growth rates differ slightly between genders. The lines on a growth chart are called ‘centile’ lines and show the range of normal weights and heights – the charts have nine centile lines: the 0.4th, 2nd, 9th, 25th, 50th, 75th, 91st, 98th and 99.6th centiles. As an example, if your child’s weight is on the 25th centile, it means that if you compared 100 children of the same age and sex in order of weights, your child would probably be number 25; 75 children would be heavier than your child, and 24 would be lighter. The weights and length/height of most children will lie between the 2nd and 91st centiles.
The value of your child’s own growth chart is having an expert measure and plot your child’s growth over time. Each child is different, and it is perfectly acceptable for a healthy child to be on any one of the centile lines – being on the 50th centile is not the ‘gold standard’ by any means! In general, weight in particular will vary more around a centile line than length/height. It is normal for children’s weights to rise and dip above and below their line at some stage. If your child loses weight or their weight varies more than 2 centile lines in-between measurements, it is important that you see your health visitor, paediatric dietitian or GP about this.
The Royal College of Paediatrics and Child Health suggest weighing your baby no more than once a month between 2 weeks and 6 months of age, no more than every 2 months up to 1 year of age, and no more than every 3 months after that, unless there are special reasons or your health professional has recommended more frequent measurements. Weighing too frequently can cause unnecessary worry and weights measured over a longer time are more likely to show the true weight change. After the age of 2 years, your child’s weight and height can be used to calculate your child’s centile for body mass index (BMI). This is now done regularly in most schools and the emphasis is on treating and preventing overweight in childhood.
In 2009 the UK-WHO growth charts were launched to cover all babies from 32 weeks gestation to the age of 4. These are an exciting development in the field of child measurement, as they are based only on the growth of healthy breastfed infants around the world. These charts account for the fact that breastfeeding produces optimal growth patterns and all children – breastfed or not – should aspire to this ideal pattern of growth.