The Red Book - interpreting Growth Charts

The red book! We’ve all been given one by our midwife or health visitor shortly after the birth of our bundle of joy. This is your Child Development Record and amongst its pages you will find your baby’s growth charts.

How your baby grows in the first year of life terms of her weight and length is linked to her future health. This is why each baby born in the UK is issued with their ‘red book’ and why your Health Visitor likes you to pop along to the baby clinic to have her weighed at regular intervals.

The charts were created by measuring thousands of babies born between 1997 and 2003 from 6 different countries who were born at full term, who were healthy and who had mummy’s who didn’t smoke and enjoyed a healthy pregnancy. The babies were all predominantly breastfed for the first 4 months of life and were introduced to weaning foods by 6 months with continued breast milk throughout their first year.  The researchers producing the charts were aiming to capture what optimal growth looks like.

Therefore the growth charts in your red book describe how a baby should grow in pursuit of good health and are there to be used by parents and health care professionals together to assess whether your baby is thriving in the way we would expect.

The lines on the growth chart are called centiles and show the expected pattern of growth. The numbers refer to the percentage of babies at or lower than the line, for example 50th centile means 50% of children are the same weight (or length) or less. 

What normal growth looks like?

Your baby’s growth should follow a centile curve throughout their first year. They don’t need to be on an actual line, they can be between them, so long as their growth follows the shape of the curve.  They don’t have to be on the same centile number for both weight and height, that’s what makes us all unique. Some of us are tall and thin, others shorter and heavier. Nevertheless, the majority of babies should track the same pattern throughout their first year and throughout childhood.

Gaining too much weight

Sometimes a babies weight goes up too rapidly and moves upwards across the centile lines. Research tells us that this is sometimes a result of overfeeding - usually milk feeds. Rapid weight gain during the first year of life is associated with increased risk of obesity later in life and may be a predictor of heart health although studies so far have been inconclusive. If you want to understand how much milk your baby should be having click here for my guide. Sometimes babies who gain weight rapidly also gain height velocity too and grow up to be taller individuals.  Unusual weight and height gain can sometimes can be an indicator of an underlying problem, so if you notice this talk to your health visitor, it may be that a referral to a dietitian is warranted to assess how much she is eating and drinking or a referral to a paediatrician is needed for further investigation. 

Not gaining enough weight.

Conversely a sudden weight loss and centile drop can occur following a period of illness, which usually recovers within 2-3 weeks, however if the drop continues through two or more centile lines talk to your health visitor or GP, it may be that your baby needs some extra help to regain his weight.

When babies start to re-gain weight after a period of faltering growth (or if they were born small for their age and are exhibiting ‘catch-up’ growth) care must be taken to ensure that weight gain is not too rapid. This too is linked with having an altered body composition and higher fat mass in both childhood and as an adult, which has its own health consequences. A Registered Dietitian can support you through this process.

How to weigh and measure your baby accurately

Babies should be weighed in no clothing if possible; even a clean nappy can make a difference to where they fall on their chart. Only use the scales that your health visitor provides as these are calibrated for accuracy.

For the first year your baby’s length is measured lying down. Again with no clothing, shoes or nappy. Specialist measuring equipment is required; your health visitor may have a special mat or board. Two people are needed to ensure an accurate height measure is taken and it’s important one of these is a health care professional. After 1 year of age, standing-height is measured instead. It’s not unusual for baby clinics to not routinely offer length measurements, it takes two people and NHS resources are stretched. Many clinics are run by support workers rather than Health Visitors and some even encourage parents to self weigh their babies, mine did. You may need to request an appointment if you want your baby’s length to be measured.

Your baby should be weighted a week or so after birth, then at 6-8 weeks, 12 weeks and 16 weeks. A lot of parents are tempted to weigh their babies more frequently than this but its important not to do so more than than once a month up till 6 months of age then once every 2 months between 6 and 12 months of age. This is because natural fluctuations take place and can be misleading and worrying for parents and health care professionals.

When your baby is weighted for the first time in the week or so after birth, there are no centile lines on the growth chart to plat them against. This is because weight fluctuates a lot from baby to baby during the first two weeks of life, so there is no expected standard. The vast majority of babies will be around the same weight as their birth weight at 2 weeks, often babies lose weight during this period and then regain it. Being the same weight or more at 2 weeks of age is an indication that feeding is going well and that your baby is healthy.

The growth charts in your red book go up to 20 years of age for boys and 18 for girls as this is when growth stops for the vast majority of young people.  From 2 years of age you can continue to weigh and measure your child at home and record their measurements on the pages given.

Further information:

If you’ve found this post useful and want to know more about your baby’s nutrition and growth during their first year of life, I host an Online Weaning Masterclass. To find out more or sign up click here for my Courses page.