Evaluation of growth rate in height over periods of less than one year.

The stature of 260 well-nourished children aged between 7 and 10 years was measured at intervals of approximately 1 month over 13 months. The growth rate of each child was calculated over periods of 3 months and 6 months ending in each month of the year. Children who missed one or more measurements, due to absence from school, were excluded from the calculations Centiles of growth rate for these periods are presented. A growth rate of 3-4 cm/yr is well within normal limits for a period of 3 or 6 months ending in December or January, but is below the 10th centile for periods ending between March and June. Most children reach their maximal 3-monthly rates in the periods of either 3 or 6 months ending between March and July, and their slowest in the periods ending between September and February. A child's growth rate over the 3 months of fastest growth is most frequently 2 to 3 times his slowest rate, but may be 7 or more times the slowest if the latter was very low. There may be no measurable growth during a single period of 3 months in a normal child, but maximal rates of up to 10 cm/yr are not necessarily abnormal. An individual's maximal 6-monthly rate may be up to 3 times his minimal. A satisfactory assessment of a child's growth cannot be made over a period of less than one year.