Pubertal growth

The onset of puberty is a wonderful event for the child if not the parents. The curiosity is why it happens at this age. Why is the latent growth delayed. It is also interesting that the age of puberty and the so called growth spurt varies form child to child. Some children continue growing long after others and after a slow start grow more that expected.
Indian, Japanese and US children have similar growth patterns up to the age of 9 years. Thereafter a growth gap develops during the remaining years of growth between the first two nationals and the US adolescents. It is not clear whether this difference is environmental or genetic. The Indian and Japanese diet is largely cereal-derived and there may be dietary deficiency or dietary antinutrients which cause the lack of growth. A survey by the Japanese Ministry of Education in 1992 of 700 000 children aged between 4 and 18 years showed they had grown significantly in height compared with their parents. Boys aged 13–14 years old were 9.5 cm taller and 9 kg heavier than their parents at the same age. At 17–18 years these Japanese in 1992 were 5 cm taller than 30 years ago. Much of this difference was in leg length.
In the Netherlands, there is a tradition of monitoring children’s height that goes back to the 19th century. During the last century and the early part of this century differences of 5–11 cm at various ages were noted between those children whose fathers had a ‘low’ as compared with a ‘high’ occupational status. This gap is now reduced to differences of 1–3 cm. Similar reduction in height differentials between socially and economically disadvantaged and rich children have been observed in India. A British tradition, unproven except in folklore, is that the child’s height at 2 years 6 months is half that of the final growth achievement.
A curious feature of the development of the stunted child is the anatomy of the deficient height. This may be the sitting height, that is, coccyx to top of head or standing height where leg length is important. In stunted USA blacks and Australian Aborigines the sitting height is deficient; in Japanese, standing height is deficient and in Indians the deficit is symmetrical. Possibly some complicating micronutrient is deficient or the timing of the deficiency at some vulnerable period occurs primarily affecting trunk or leg growth.

Martin Eastwood
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