Growth In Childhood

Terence J Wilkin

• Editorial: Routledge
• Año: 2021
• ISBN:
  9781134338337
• Edición: 1
• Categoría: Medicine
• Categoría: Health Care Delivery

First Published in 1989 this is a collection of essays based on a series of lectures given at a symposium held at the University of Southampton Medical School from eight experts in the field of growth failure. Interest in growth hormone, its regulation and its therapeutic use has grown enormously since the introduction of genetically engineered growth hormone in 1985. The very pratcial probelms of measuring growth, the physiology of growth failure and its epidemiology are followed by a richly illustrated chapter on the spectrum of diseases assciated with short stature and an expert with extensive experience in the field looks at the application of growth hormone therapy.

Growth Measurement

JOHN BUCKLER

Senior Lecturer in Paediatrics and Consultant Paediatrician, University Department of Paediatrics and Child Health, D Floor, Clarendon Wing, The General Infirmary at Leeds, Belmont Grove, Leeds LS2 9NS, UK

A review is presented of the history of growth measurements and surveys of growth. The relevance of growth measurements, the importance of accuracy in longitudinal observations and the factors associated with accuracy are discussed. The use of centile charts and what determines their appropriateness are considered.

KEY WORDS: Anthropometry, auxology, puberty, growth spurt, growth studies, accuracy, centiles

HISTORICAL BACKGROUND

In discussing the subject of the history of growth measurement, reference must be made to the writings of Professor Tanner, to whom I am indebted not only for my personal interest in and knowledge of auxology but, in this particular context, for his excellent book “A History of the Study of Human Growth” (Cambridge University Press, 1981), a comprehensive and invaluable source of material upon which I have drawn extensively. This volume provides the interested reader with as much information as he could possibly want.

Prior to the last 200 years or so, interest in the physical body and its growth was related much more to body proportions than to actual size. Elsholtz, a German physician, in the mid 1600’s first used the term anthropometry and devised an anthropometer whose mechanism was much more orientated to demonstrating relative size of components of body height than the actual height itself. It was not until 1795 with the introduction of the metre that there was any precise length standard, and values for length had no consistent basis and varied from place to place.

The importance of height for military recruits in the 18th and 19th centuries was a reason for the development of interest in height as such, and Goethe, at one stage being involved in recruiting, drew a sketch in 1779 demonstrating remarkably good measuring technique.

The first and still one of the best recorded longitudinal studies of growth, now very familiar, was the record by Count Montbeillard of the growth of his son in the years 1759–77, made at the request of Buffon and published in the 4th set of 7 volumes of his supplements to the Natural History. There is no comment on the measurement techniques except that all were undertaken by Montbeillard himself at 6-monthly intervals and with his son barefoot, and the graphical presentation and derived height velocities indicate the precision and care of his methods.

The Belgian genius Quetelet, whose interests covered a vast range of scientific subjects and who undertook the first population survey of children in 1831–32, also recorded the longitudinal growth data of two of his own children and two daughters of friends. He would not, however, recognize the apparent growth spurt, but smoothed his curves, being convinced that “l’homme moyen (average man), at least, should have a growth curve of perfect regularity and impeccable form.” (Tanner).

Others through the years have measured their own children and one of the most meticulous was Christian Wiener (who used the concept of decimal age 100 years before Tanner) who measured his 4 sons between 1856–90, initially annually, but with greater enthusiasm and frequency as new ones appeared, so that the last was measured 89 times. These sons showed unequivocal growth spurts, but interesting variations in the ages of peak height velocity, 13.2, 13.5, 14.5 and 12.5 years.

[A rather more recent family study is now presented of my own three boys measured through the years of puberty, which shows a similar variation, with peaks at 13.5, 14.2 and 15.2 years, Figures 1–3.]

In England epidemiological growth studies were first carried out as the result of the Factory Commission of 1833. These studies measured the heights of 2000 boys and girls who had worked in a factory from an early age, and demonstrated that these children were stunted. Subsequently Charles Roberts took an interest in the growth of children through his involvement in a Parliamentary Commission in 1872–73 studying the growth and welfare of nearly 10000 North of England factory and other working class children. He demonstrated a striking difference between the heights of the children of manual and non-manual workers. Roberts also observed the great variation around the mean, and noted how misleading mere averages could be.

FIGURE 1 Height centiles of 3 brothers (1974–1987).

Francis Galton, about the same time as Roberts, transformed the study of growth in this country. Recognizing the need for information countrywide about children’s growth he sponsored in 1873 a programme of body measurements in schools. He developed a stadiometer basically the same as the modern Harpenden instrument and interpreted distribution in these accurately obtained values in terms corresponding to standard deviation. He also developed other important statistical concepts. Through a large family study of nearly 10000 persons he was able to demonstrate the importance of familial factors in growth, and showed how to present data in terms of centiles. He also interpreted, years before anyone else, the misleading effects in growth curves at puberty of averaging cross-sectional data, and stressed the need for longitudinal growth studies on individuals.

FIGURE 2 Weight centiles of 3 brothers.

In the USA interest in growth started with the work of Henry Bowditch, who in 1872 presented 25 years worth of growth data of 25 closely related individuals. He went on to undertake a massive survey in state and private schools (24 500 children) and presented data as height charts through the years. He noted the different timing of the growth of boys and girls but, like many others, he missed the significance of the different growth patterns of early and late developers in explaining differences between social or ethnic groups.

FIGURE 3 Height velocity centiles of 3 brothers, (a) Plotted according to chronological age. (b) Plotted in relation to the ages of peak height velocity.

[Bowditch’s studies were followed up in other areas of the States by Peckham and Porter, the latter pointing out (1920) that centiles represented what the overall distribution was, not what it necessarily should be.]

Schools surveys had also been undertaken in other countries, notably by Pagliani in Italy who in a paper in 1897 demonstrated the growth spurt following the period of slowest growth, but he was the first to recognize the significance of the different timing of pubertal growth in individuals, which effect is obscured in composite means. He showed, contrary to his predecessors, that puberty (reproduction) and growth go in parallel, both dependent on the same underlying influence, as illustrated in girls by the growth spurt being linked in time with menarche, preceding it by between 1 and 2 years, whatever the age of menarche. Following Pagliani, school surveys were undertaken in many other parts of Europe and by 1900 growth curves were available for many countries.

The credit for first recognition of the significance of the difference between individual and composite growth patterns is however usually given to Frank Boas who as well as initiating the first large longitudinal growth study also produced in 1898 composite North American standards based on about 90000 children. However in 1892, shortly after Pagliani and independently, he pointed out that almost all individuals deviate from the composite centile position at puberty, but not until 1930 did he show that each individual has a maximum growth age, demonstrated by velocity curves which vary over a wide age range among the population of adolescents. It was he, probably, who originated the term “physiological age”. He showed that early developing boys were taller by age 11, but did not necessarily end up taller, and the earlier the age of maximum growth rate, the higher was this peak height velocity.

Boas’ work was confirmed and followed up very soon by the massive Harvard longitudinal growth study, started in 1923, in which nearly 1000 children were measured annually from age 6 to 18. This was reported by Frank Shuttleworth in 1937 in a very comprehensive monograph which forms the basis of the modern understanding and appreciation of growth studies. He emphasized the need for the vast potential information of longitudinal studies to be used to demonstrate increments of growth, i.e. velocities, rather than losing this information in cross sectional presentation of gross measurements. He showed the value of comparing individuals’ velocity curves for each parameter in terms of maximum growth age. This enabled demonstration of relationships of timing of growth of different body dimensions, and comparison of growth patterns of early and late developers. Surprisingly Shuttle-worth’s writings did not correlate growth patterns with secondary sexual characteristics, which had first been used in a graded way by the pioneer in growth surveillance, the French physician Paul Godin, in the early years of this century.

The importance of rating and relating secondary sexual characteristics has been much emphasized in the more recent Harpenden Growth study of Tanner and Whitehouse. This is a very comprehensive study undertaken on 228 boys and 192 girls between the years 1948 and 1971, with frequent observations through the years of puberty. In addition to presentation of growth data of many other body dimensions than just height and weight, interrelationships are demonstrated and in particular the range of variation of pubic hair, genital and breast development, graded according to the widely used descriptions of Tanner. The accuracy of measurements is established by the fact that they were all undertaken throughout by one observer only, Whitehouse himself, using instruments which he had personally designed and whose accuracy far surpassed those previously in use whose design had been unchanged for many decades.

THE NEED FOR GROWTH MEASUREMENT

Only by measurement is it possible to recognize the significance of dimensions of individuals and groups when these are compared appropriately against standards of overall populations. Mere impressions can be very misleading. Bowditch in 1881 pointed out that there was value in measurement in two directions, in the comparative health of populations and large scale identification of deprived areas and also in the recognition of growth problems of individuals. During this century numerous school surveys have been carried out in the Western world and such large scale surveys have established many general fundamental facts such as the adverse effects of overcrowding. It is important, however, to stress the distinction between comparisons of populations which indicate the need for improvements in general social and health standards, and observations on individuals which indicate the need for specific treatment.

Some countries have pioneered in population growth monitoring, notably several surveys in Holland since 1955. Little was done in Britain prior to 1972, but since that time, as the result of concern emanating from the restriction of free milk in schools, the National Study of Health and Growth has monitored growth in primary school children aged 5–11 and the Pre-School Child Growth Survey in children from birth to 5 years. These surveys are still continuing.

One of the pioneers in recognizing the value of measurement in both these aspects, the relevance to the group and to the individual, was Paul Godin who in 1919 first coined the term “auxology” which he defined as “the study of growth by the method of following the same subjects during numerous six-monthly periods with a great number of measurements”. Godin’s meticulous application of measurements has, as Tanner points out, only been equalled by Whitehouse. Godin personally undertook 129 measurements on each boy on about 1000 total boy–occasions (very similar to Whitehouse’s total of 15 measurements on 9000 child–occasions). Single measurements correctly interpreted on centile charts may well be the trigger that alerts an observer to a potential problem, but serial measurements that show a fall off in growth velocity are of greater value and provide one of the surest signs of ill health.

THE DIFFICULTIES IN OBTAINING RELIABLE SERIAL MEASUREMENTS

The need for accuracy

A relatively minor degree of inaccuracy in any measurement in the “one-off” observation circumstance may not be critical or render the observation valueless. The effect of this degree of error when plotted to give a centile position may be relatively trivial, and is unlikely to be so great as to alter the interpretation of its significance or to miss recognizing the need for concern and action. Recording such values for reference in the distant future will also provide useful information (particularly if the limitations of the technique are recognized), for if the interval between observations is long enough, the effect of inaccuracy will be small compared with the overall expected growth change, and deviation from centile positions would still be apparent..

However, in those situations where these initial measurements have given rise for concern, the need for frequent follow-up becomes highly important and with it the need for as great a degree of accuracy as possible. An error which is lost in the overall accumulated growth of several years is highly significant over intervals of a few months or even a year and inaccurate measu...