Investigation of the mid-growth spurt in height, weight and limb circumferences in single-year velocity data from the London, 1966-67 growth survey.

In the 1966-67 London County Council Survey, some 10 000 children were measured twice, on occasions one year apart. Mean single-year velocities were calculated for each successive 6-month period from age centre 5 1/2 to maturity, for height, weight, upper arm and calf circumferences and triceps and subscapular skinfolds. The velocity curves, in which successive points are independently ascertained, were examined for evidence of a mid-growth spurt. In weight and limb circumferences there was a clear increase of velocity occurring from about 6 1/2 to 7 1/2 in girls and from 7 to 8 in boys. From the end of the mid-growth spurt to the beginning of the adolescent spurt, about three years later, weight velocity remained constant, but limb circumferences velocities mostly dropped. All or most of these changes in velocity can be accounted for by changes in rate of fat deposition. Girls showed no evidence of a mid-growth spurt in height, but boys had a diminution of deceleration, or relative spurt, from about 6 to about 7. These results could be accounted for if some, but not all, individual children have mid-growth height spurts. Graphs of the single-year actual-increment medians show slight differences from the standard population velocity medians, the actual-increment curves being a little more complicated than the smoothed standards.