What is the best way to measure waist circumference?

Waist circumference is a measure of potential value in paediatrics, given its relation to cardiovascular risk in adults. However, three different methods of measurement are currently in use, giving potential for confusion. This study was undertaken to assess consistency across the measures in a population of overweight and normal weight children. We found that when expressed as standard deviation score (SDS) on the British 1990 reference, all three methods correlated highly with body mass index standard deviation score (BMI SDS); however, there was bias and variability between the measures. Based on ease of measurement, the site 4 cm above the umbilicus was the most convenient. This method was also endorsed by children's views. We therefore recommend that 4 cm above the umbilicus is adopted for clinical use until such time as the methods are verified against the gold standard of visceral fat, as measured by magnetic resonance imaging scan.