Sunday July 17, 2011
Children have different growth rates, but with a standardised BMI chart, parents and healthcare providers can keep track of whether they are growing normally.
HAVE you ever wondered whenever you look at your child’s class picture that children from the same class, and in the same age group, come in various shapes and sizes?
Some children might look tiny and scrawny standing next to their friends, but others will literally stand out head and shoulders above the rest.
A student having her height and weight measurements taken to calculate her BMI. — File photo
You might easily make some comparisons, but in reality, each of us grow differently.
Growth rate differs according to gender, age and other environmental factors, and many of these factors vary from one family to the other. However, growth rate tends to follow standard patterns.
So, how do we know whether our children’s growth is normal? Is there any yardstick we can use to keep track of it?
Body measurements such as height and weight are important indicators in population health to evaluate a child’s well-being in terms of nutritional status and physiological needs and to identify any growth discrepancy.
These measurements are normally compared to a reference chart to determine the growth status.
Subjects who are unusual in the sense that their measurement for a particular trait lie in one or the other tail of the distribution curve will be determined, thus helping clinicians and public health workers to diagnose growth-related conditions.
Since the late 1970’s, the National Centre for Health Statistics (NCHS) World Health Organisation (WHO) growth reference chart has been in use to chart children’s growth worldwide.
WHO released a growth reference chart for school-aged children and adolescents in 2007.
The 2000 CDC growth charts consist of a series of percentile curves that illustrate the distribution of selected body measurements in US children.
They represent the revised version of the 1977 NCHS growth charts. This revised growth charts consist of charts for boys and girls aged two to 20 years, including body mass index-for-age (BMI-for-age) aged two to 20 years, which provide an improved tool for evaluating the growth of children in clinical and research settings.
When doctors or healthcare providers plot a child’s BMI number on the chart, they will be able to see which percentile line that number lies.
The percentile indicates the relative position of the child’s BMI number among children of the same age and gender. The higher the percentile number, the bigger a child is compared with other kids of the same age and gender. On the other hand, the lower the percentile number, the smaller the child is.
Being in high or low percentile does not necessarily mean that a child is healthier or has growth problems.
How do you define a good or a bad growth? A child has gained enough weight if the curve is going up and the slope is parallel to one of the references curves. Even if the child is small, the growth curve should still go up and should be parallel to one of the reference curves to show the child is growing well.
On the other hand, the child’s growth is static if the curve is flat. This is a dangerous sign that needs to be further investigated.
A child has lost weight if the child’s growth curve shows a downward direction. A child’s growth is slowing and the weight gain is less than expected if the curve is less steep than the reference curve.
Doctors in Malaysia have been using the CDC or the WHO charts to assess our children’s growth.
International growth charts allow comparisons to be made between different countries, but regional or national references are more useful in the assessment of local changes in nutritional status.
The need to develop an appropriate single reference centile chart for screening, surveilance and monitoring of school-aged children and adolescents has been motivated by increasing public health concern over childhood obesity, as well as a lack of an acceptable local reference for growth evaluation for Malaysia.
Early studies on weight and height curves for Malaysian school children was highlighted and recorded by ST Chen and AE Dugdale from Universiti Malaya (published in the Medical Journal of Malaya in 1970).
Having a nationwide study to access growth in terms of height and weight involving an appropriate number of children and adolescents to represent the current population of that age is therefore necessary in view of the rapid changes in the country’s economy, lifestyle and nutritional status.
Against this background, a research team from the Universiti Malaya (UM) has conducted a comprehensive nationwide cross-sectional study to model the growth curves of Malaysian school children ranging from 7 to 17 years old, and consisting of Malays, Chinese, Indians and several indigenous groups. The study was supported by a UM research grant and data was collected with permission from the Education Ministry.
The study has successfully developed a standardised BMI chart for schoolchildren in Malaysia.
This cross-sectional study is based on data obtained from a sample of about 14,000 from schoolchildren all over Malaysia.
The results show the average BMI scores of each age category of our children: BMI scores at or more than 97th percentile: obese; BMI scores between 90th percentile to 97th percentile: overweight; BMI scores between 5th percentile to 90th percentile: healthy / acceptable weight; BMI scores between 3rd percentile to 5th percentile: underweight; BMI scores less than 3rd percentile: severely underweight.
The majority of children who are overweight are also obese and need help with weight management.
Obese children are at higher risks of becoming obese adults and increased risk for chronic diseases later in life, including cardiovascular disease and diabetes.
With the development of these reference charts, parents, teachers and health providers can perform their own evaluation to determine whether their children are growing normally or otherwise.
This article is written by Assoc Prof Dr Asma Ahmad Shariff (Applied Statistic), Assoc Prof Dr Abdul Majid Mohamed (Biostatistic), Assoc Prof Dr Amir Feisal Merican (Computational biology) and Assoc Prof Dr Zilfalil Bin Alwi (Consultant Pediatrician, USM), and Bong Yii Bonn (PhD candidate), Universiti Malaya.