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It’s common to suspect poor growth in your child. “There’s no way my child has followed his growth curve.” As a pediatrician, I investigate many cases of poor weight gain and poor height growth. I see many curves that are completely normal but have caused concern in parents.
How do you read a growth curve?
The growth curve is made by measuring the weight and length or height of several thousand seemingly healthy children, many times during their upbringing and marking the measured values to form a graph (or entering them in a computer program rather).
A thick line (the middle curve) is drawn in the middle so that half of the children at a certain age are larger than the line and half are smaller. Subsequently, a line is drawn where one third of all children are larger and two thirds are smaller (+ 1SD is the name of the curve) and another line is drawn where two thirds of all children are larger and one third are smaller (-1 SD). The next curve is where two out of a hundred children are larger and 98 out of 100 children are smaller (+ 2SD). Similarly, two out of a hundred children are smaller and 98 out of 100 children are larger than the curve (-2SD). The middle curve is often called the ‘normal curve’. Its mathematically correct name is misleading and can often cause distress in parents. The space between the curves are called ‘channels’.
If you have a fully breastfed baby that is starting to diverge from the growth curves provided by your medical center, you can easily refer to WHO’s growth curves. WHO’s growth curve is extrapolated from 8500 fully breastfed babies from 6 countries all over the world. If your baby follows that curve, everything is fine.
Is it best to follow the normal curve?
No. It’s not necessarily the ‘best’. The normal curve is made so that half of all healthy children should be larger and half should be smaller. Therefore, it is just as healthy to grow in parallel with the other curves. That’s why I think it’s silly to call it the ‘normal curve’ because “normal” in everyday language often implies “good” or “healthy” etc. I usually call it the ‘mean curve’ which mathematically means the average, and not that the curve isn’t nice.
An important thing to remember is that a child who follows their curve, grows well. Even if the little child only picks at their food and eats small amounts, as long as they are following the curve, they are eating enough.
What is poor growth?
Healthy children usually grow approximately parallel to the curves. They are said to ‘follow their curve’. A child who grows slower than their curve, and thus moves from +2 SD to + 1 SD and perhaps towards the mean curve, may have poor growth. But it can also be a normal variation in breastfeeding children. As a pediatric nurse, school nurse and pediatrician, you learn to recognize these patterns and deviations.
Measurement errors are the most common reason for deviation
It is not easy to measure children while they’re kicking and screaming. Measurement errors or a carelessly entered “estimated weight” in a medical record system are the most common reasons why children do not follow their curve. Measure and question previously deviating measured values.
Height or length follows the weight
If a child deviates from the curves, whether up or down, then either the weight or the length deviates first. In general, the height or length follows the weight. A weight gain is thus eventually followed by an increase in height or length and a loss of weight followed again by a slow increase in length.
If the length or height deviates from the curve before the weight, there may be more reason to investigate for the underlying disease.
Poor weight gain
Poor weight gain (where the weight deviates from the curve before the length or height) can be due to the child ingesting too little food, absorbing too little food in the intestine or wasting a lot of energy.
In a doctor’s assessment of poor weight gain, this is all investigated. Most often, a test for celiac disease (or gluten intolerance) is undertaken, some other basic tests and a general medical examination is included.
A dietitian’s assessment of the child’s food diary is also useful to see if the child is getting too little energy.
Poor weight gain during the cold season
In principle, all illnesses can affect a child’s growth. Colds, ear infections and stomach illnesses reduce appetite and children lose a little weight or stays the same weight for a week or two. If the child has many, frequent infections, their growth is affected for a longer period of time. It may be best to just wait and see how the child grows when the cold season has ended.
Common diseases that can cause poor growth
Children with asthma, who cough and have breathing problems throughout the winter season, often grow worse if they do not receive treatment. Children’s growth usually improves when asthma is treated well.
Children with constipation who are not treated well, often feel ill, have a stomach ache and poor appetite. If the child often has hard poo, or has been diagnosed with constipation, make sure to treat it properly and see if their growth improves.
Unusual diseases that cause poor growth
Chronic diseases in children can also affect growth. However the majority of children with poor weight gain, do not have a chronic disease. In heart disease, the heart needs so much energy to work that the child is not able to eat enough to meet the heart’s demands. In lung disease, so much energy is required for breathing that the child is not able to eat. In gastrointestinal diseases (such as food allergies, gluten intolerance and inflammatory bowel diseases), the intestines cannot absorb enough nutrition to meet the child’s needs. In all diseases that cause inflammation (almost all to some degree), the inflammation causes the appetite to decrease and growth to slow down.
Stress in the family and poor growth
In a stressed and pressured family environment, children often respond by growing poorly. Maybe the appetite reduces. Maybe it’s something in the child’s metabolism that has changed. You don’t really know and it’s hard to tell. It is clear, however, that when stress eases, children grow better again.