Body Mass Index Reference Data for Shiraz (South of Iran) School Children in relation to CDC Standards

Background: Body mass index (BMI) reference data for school children in ages between 6.5 to 11.5 years in Shiraz (South of Iran) are presented. Materials and method: The data are based on a random multi stage sample survey of 2397 healthy school attainders (1268 boys and 1129) living in Shiraz, whose height and weights were measured in 2002-2003 academic year. Joint height-weight measurements were available for 2195 (91.6%) including 1138 boys (89.7) % and 1057 girls (93.6) %. Healy-Rabash-Yang (HRY) distribution-free method was applied to estimate BMI age-related centiles. Results: Cubic polynomials in age are shown to fit the BMI data (on log scale) adequately. Children are now heavier than those born over ten years earlier. Boys BMI lie above girls in around age 10, which the direction changes later on for overweight and obese centiles. Conclusion: Comparison of these BMI curves with the corresponding CDC charts showed substantial differences at every age and suggests the necessity for the use of locally based BMI norms for assessing body of Shiraz (South of Iran) children. Also, a positive secular trend in BMI is seen during the past decade in Iran.