Are growth curves for Iranian school-aged children different from the NCHS standards?

Assessment of physical growth in school-aged children is important for the assessment of nutritional status, promotion of health and learning ability of children. Assessment of physical growth is the main purpose of this research.

This cross-sectional study was performed on 2615 healthy school-aged children (6-11 years old) in the Autumn of 2006 using two-stage stratified cluster sampling for measurement of weight and height. Sample size calculation was performed using EPI info 6 software. Statistical calculations and calculation of raw growth percentiles were performed using Statistical Package of Social Science program 15.0.

The findings showed that boys less than 9.5 years of age were heavier than girls of the same age, while girls were heavier thereafter. Similarly, the average height of boys till 10 years was higher than the girls, but girls surpassed boys after 10 years of age. The fifth centile of boys' height at the ages of 6 and 7 years was higher than the same centile in the National Center for Health Statistics (NCHS). In all centiles and all ages, the height of Abadanian girls was below the age-matched NCHS centiles. This difference was significant in 6 (P=0.003), 7 (P=0.007), and 11 years (P=0.002). The results showed that at the age of 6 and 8 years, the 50th centile of the weight of Abadanian boys was slightly below the 50th centile of NCHS. At the age of 6 and 7 years, the 50th centile of girls weight was close to the 25th centile of NCHS, and as the age increased, it shifted upward, to come close to the 50th centile of NCHS. This difference between our study and NCHS girls' weight curve during the 6-11 age period was significant (Z-test, P<0.0001).

There are some significant differences between the Iranian and NCHS growth parameters. It may be necessary to define new national growth parameters to assess our child health status.