The Norwegian Institute of Public Health is responsible for collecting and analysing the results for the Child Growth Study in Norway (Barns vekst i Norge). Data collection for the 2010 study is completed, with a high participation rate of 87 per cent from 130 schools. The data are now being analysed.
Every two years
Eight- to nine year-old children at primary schools across Norway are invited to participate in the Child Growth Study in Norway. Schools are chosen at random and participation is voluntary. The first study took place in 2008 with 3,511 eight year olds from 127 schools across Norway and will be repeated every two years with a new group of children. In 2010, data was collected from 130 schools and are now being analysed. The results are expected in early summer 2011.
Summary of the study
Before the study begins at each school, parents will receive a letter with information about the study and a consent form. The child can only participate once the consent form is completed and returned to the school health service.
Each child will be measured individually in the school health service’s office. Height, weight and waist circumference are measured while the child is wearing light, indoor clothing. The child’s waist circumference is measured at navel height.
Measurements must only be taken using calibrated equipment for which there are strict instructions.
The school health service will also provide information about each school with regards to physical activity, school meals and which kinds of beverages students have access to during school hours.
For adults, a body mass index (BMI) of 25 to 29.9 kg/m2 is defined as overweight and 30 kg/m2 and higher is defined as obesity. For children aged 2-18 years, BMI-definitions for overweight and obesity are adjusted by age and sex (Cole index / IOTF definitions).
The waist circumference is also included in the Child Growth study. The purpose is to follow the waist circumference in future studies to see if this can be an indicator for weight development and health.
Waist-to-height ratio is defined as waist circumference divided by height. A ratio of 0.5 and above is considered "high waist-to-height ratio." This means that the waist circumference should not be greater than half the height. In the study, the average waist-to-height ratio is 0.44 for both girls and boys. 9 per cent of girls and 7 per cent of boys had a waist-to-height ratio of 0.5 or more.
The child is not given the results of their measurements. Parents who wish can obtain the results by contacting the school health office. The combined results from Norway will be ready in the spring following collection.
Measurement results are anonymised, and the results are analysed on a group level by gender, county and entire country. Data from Norway will be compared with data from other European countries.
A large collection of measurements will give a reliable picture of Norwegian children’s growth in 2008. In addition, we can see whether height, weight and waist circumference have changed since the last nationwide study which took place in 1971-74. The measurements can also be compared with local measurements from Bergen and Oslo in 2003-2006. We need at least 70 per cent participation to ensure high quality data.
Oslo, Akershus, Rogaland, Vest-Agder, Rogaland, Hordaland, More og Romsdal, Sør-Trøndelag, Nordland, Troms.
Schools from municipalities in each of the counties have been invited to participate, making a total of 130 schools.
Who is responsible for the study?
The project is a collaboration between the Norwegian Institute of Public Health, the Norwegian Directorate of Health, WHO and the public health nurses. The initiative comes from the WHO, and similar studies are being carried out in about 20 European countries.