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Background: Children with achondroplasia (ACH) appear to lack a pubertal growth spurt in height. Aim To explore the growth spurt in height and its segments sitting height and leg length, in a large sample of ACH cases using growth curve modelling. Subjects and methods: Height and sitting height were measured longitudinally in ACH children, and the data were analysed using the SITAR (SuperImposition by Translation and Rotation) growth model, which estimates a mean growth curve and random effects for individuals defining differences in size, pubertal timing and intensity. Results: Out of 402 ACH children, 85 boys and 75 girls aged 7-20 years had respectively 529 and 454 measurements of height and sitting height, with leg length calculated by difference. SITAR analysis identified peaks in mean height velocity at 13.3 and 11.3 years in boys and girls, with peak velocities of 4.3 and 4.4 cm/year. Mean peak velocity for sitting height was 3.0 cm/year, but leg length showed no peak. The SITAR models explained 92% to 99% of the cross-sectional variance. Conclusion: ACH children do experience a growth spurt in puberty, but only half that of control children. The spurt is due entirely to sitting height, with no leg length spurt.

Objectives Japanese and South Koreans have traditionally been shorter than Europeans, but have recently become appreciably taller. The aim was to quantify the secular trend patterns in height and weight growth in the two countries over 50 years using the SITAR growth curve model. Methods Data on mean height and weight by sex in 1-year age groups from 1 to 20 years were obtained by decade in South Korea (1965-2005) and Japan (1950-2010). The data were analyzed using SITAR (SuperImposition by Translation And Rotation), which estimates a mean curve and three adjustments-size, timing and intensity-reflecting how the individual surveys differ from the mean. A sensitivity analysis compared results for the Japanese data based on cohort as well as period. Results Growth patterns in the two countries changed dramatically over the study period, affecting not only height and weight but also developmental age, in that the growth period advanced in timing and shrank in duration. SITAR fitted the data well. The trends were larger in South Korea than Japan, and puberty timing in Japan stabilized by 1970. Most of the height increment seen in adults had already accrued by age 1.5 years, whereas the adult weight increment accrued throughout childhood. Conclusions The secular height trend in these countries represents increased growth in the long bones during infancy, so it can be viewed as the inverse of stunting. There are striking country differences in growth pattern, but they are not easily explained by differences in national income, diet or lifestyle., (© 2017 The Authors. American Journal of Human Biology Published by Wiley Periodicals, Inc.)

Mucopolysaccharidosis (MPS) VI is an autosomal recessive lysosomal storage disorder arising from deficient activity of N-acetylgalactosamine-4-sulfatase (arylsulfatase B) and subsequent intracellular accumulation of the glycosaminoglycans (GAGs) dermatan sulfate and chondroitin-4-sulfate. Manifestations are multi-systemic and include skeletal abnormalities such as dysostosis multiplex and short stature. Reference height-for-age growth charts for treatment-naïve MPS VI patients have been published for both the slowly and rapidly progressing populations. Categorization of disease progression for these charts was based on urinary GAG (uGAG) level; high (>200μg/mg creatinine) levels identified subjects as rapidly progressing. Height data for 141 patients who began galsulfase treatment by the age of 18years were collected and stratified by baseline uGAG level and age at ERT initiation in 3-year increments. The reference MPS VI growth charts were used to calculate change in Z-score from pre-treatment baseline to last follow-up. Among patients with high baseline uGAG levels, galsulfase ERT was associated with an increase in Z-score for those beginning treatment at 0-3, >3-6, >6-9, >9-12, and >12-15years of age (p<0.05). Increases in Z-score were not detected for patients who began treatment between 15 and 18years of age, nor for patients with low (≤200μg/mg creatinine) baseline uGAG levels, regardless of age at treatment initiation. The largest positive deviation from untreated reference populations was seen in the high uGAG excretion groups who began treatment by 6years of age, suggesting an age- and severity-dependent impact of galsulfase ERT on growth., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Aim: To estimate and compare pubertal growth timing and intensity in height, Tanner stage markers and testis volume., Subjects and Methods: Data on height, genital stage, breast stage and pubic hair stage, testis volume and menarche in 103 boys and 74 girls from the Edinburgh Longitudinal Growth Study were analysed. The SITAR model for height and a novel mixed effects logistic model for Tanner stage and testis volume provided estimates of peak velocity (PV, intensity) and age at peak velocity (APV, timing), both overall (from fixed effects) and for individuals (random effects)., Results: Based on the six markers, mean APV was 13.0-14.0 years in boys and 12.0-13.1 years in girls, with between-subject standard deviations of ~1 year. PV for height was 8-9 cm/year by sex and for testis volume 6 ml/year, while Tanner stage increased by 1.2-1.8 stages per year at its peak. The correlations across markers for APV were 0.6-0.8 for boys and 0.8-0.92 for girls, very significantly higher for girls (p = 0.005). Correlations for PV were lower, -0.2-0.6., Conclusions: The mixed effects models perform well in estimating timing and intensity in individuals across several puberty markers. Age at peak velocity correlates highly across markers, but peak velocity less so.

Aim: To produce a growth reference for British children with Williams syndrome., Methods: The children and adults recruited into the study were all affiliated to the Williams Syndrome Foundation, a parent support group founded in 1979. They have all been shown to have a deletion of chromosome 7q11.23. One growth nurse (WRS) prospectively measured the weight, height and head circumference of individuals from 19 regions in Great Britain including Scotland, England and Wales. 169 children and adults were measured on up to four occasions between 2001 and 2004 (275 measurements). In addition, retrospective data were obtained from the hospital notes of 67 of these individuals (586 measurements). Centile curves were constructed using Cole's LMS method., Results: The centile charts differ from charts previously derived in the USA and Germany and provide more appropriate standards for the British population., Conclusions: We propose that these charts be adopted for routine clinical practice as abnormalities in growth are an important feature of this syndrome.

Objective: To monitor the changing relationship between body mass index (BMI) and height in young children., Design: Annual cross-sectional surveys using health-visitor-collected routine data 1988-2003., Setting: Wirral, England., Participants: Fifty thousand four hundred and fifty-five children (49% female) each measured once at the age of 3 years., Main Outcome Measures: Weight, height and derived BMI (weight/height(2)) adjusted for age and sex (British 1990 revised reference) using standard deviation scores., Results: From 1988 to 2003, mean BMI increased by 0.7 kg/m(2), whereas mean height fell by 0.5 cm. Over the same period, the weight-height correlation rose from 0.59 to 0.71 (P<0.0001) owing to BMI increasing faster in the taller than the shorter children. Among the shortest 10% of children, mean BMI rose by 0.12 (95% confidence interval: -0.05-0.28) kg/m(2) as against 1.38 (1.19-1.56) kg/m(2) among the tallest 10%, a 12-fold difference. Adjustment for age, sex, seasonality, birth-weight and deprivation did not alter the findings., Conclusions: Among 3-year-old children in Wirral, where BMI has been rising for 16 years, the largest increase in BMI has occurred in the tallest children, whereas in the shortest BMI has hardly changed. Tall stature has, therefore, become important for child obesity. It suggests a drive to increasing adiposity in young children that involves both growth and appetite, with fast growing and hungrier children now more exposed to the 'obesogenic' environment.

Objective: To examine the impact of childhood body mass index (BMI) on timing of puberty, adult stature and obesity., Design: A retrospective school-based cohort follow-up study., Subjects: A total of 1520 men born between 1927 and 1956 with serial height and weight measurements from the age of 9 to 18, followed up in adulthood at a mean age of 63 years., Measurements: Prepubertal (child) BMI; age at peak height velocity (APHV); adult leg length, waist and hip circumference (self-reported), and height and weight (measured)., Results: Boys with a higher childhood BMI tended to have an earlier puberty (per s.d. increase in child BMI: -0.31 years, 95% confidence interval (CI): -0.23 to -0.39, P < 0.001). Childhood BMI correlated strongly and positively with adult adiposity, as measured by BMI (1.24 kg/m(2), 95% CI: 1.04-1.45, P < 0.001), waist (1.94 cm, 95% CI: 1.50-2.37, P < 0.001) and hip (1.91 cm, 95% CI: 1.55-2.28, P < 0.001). It correlated inversely with leg length (-0.40 cm, 95% CI: -0.68 to -0.12, P = 0.005), but not significantly with height or trunk length. Boys with a later puberty tended to be taller (per s.d. increase in APHV: 0.57 cm, 95% CI: 0.17-0.97, P = 0.006) and less adipose as adults (-0.55 kg/m(2), 95% CI: -0.33 to -0.77, P < 0.001)., Conclusion: The long-term consequences of childhood obesity into adulthood are well known, but the potential impact on early pubertal maturation is less well appreciated. The factors that contribute to the onset and persistence of childhood obesity require more public health focus.

Objective: To produce prediction equations for basal metabolic rate (BMR) derived from weight and height covering the age range from birth to old age., Design: Cross-sectional data on BMR, sex, age, weight, height, ethnicity and measurement technique from the Oxford Brookes BMR database., Setting: Worldwide., Subjects: Data for 13,910 men, women and children from 174 papers published between 1914 and 2001., Results: Absolute and proportional regression models were developed for each sex, showing a steep rise in predicted BMR with age until 15 years, more pronounced in males than females, then a gradual fall through adulthood. Predicted BMR increased by 6% and 1.4%, respectively, per standard deviation increase in weight and height. Predicted BMR in Caucasians was 4% higher than in non-Caucasians, though the effect size was sensitive to the inclusion or exclusion of data from certain influential publications. The effect of measurement technique on BMR, closed-circuit versus open-circuit, was small, near 1%., Conclusions: It is possible to develop prediction equations that avoid splitting the data into arbitrary age groups. Heterogeneity between publications is greater than might be expected by chance, probably due to undocumented differences in technique.

Background: Weight for height in children is often assessed by comparing the child's weight-for-age centile with their height-for-age centile. However, this assessment has not been validated statistically, and it differs from the body mass index (BMI) centile., Objective: To study indices of weight-for-height based on weight centile-for-age adjusted for height centile-for-age, and to see how they relate to the BMI centile-for-age., Design: Cross-sectional survey of data for 40 536 boys and girls aged 0-18 y from the 1980 Nationwide Dutch Growth Survey, using the British 1990 and US CDC 2000 growth references., Outcome Measures: Two measures of weight for height: (a) the difference between weight centile and height centile, and (b) BMI centile, with the centiles analysed as SD scores (SDS)., Results: BMI centile is correlated strongly with weight centile (r=0.77) but weakly with height centile (r=0.1). By contrast the difference between weight centile and height centile is correlated only weakly with weight centile (r=0.3) and strongly negatively with height centile (r=-0.5). BMI centile is predicted to high accuracy by the multiple regression on weight centile and height centile (93-97% of variance explained, s.e.e. 0.2 units)., Conclusions: A child's BMI centile can be calculated to high accuracy from their weight and height centiles as read off the weight and height charts. This avoids the need to calculate BMI or to plot it on the BMI chart. A chart is provided to simplify this calculation, which works throughout the spectrum of nutritional status. It can also be used to monitor individuals' weight, height and BMI centiles simultaneously as they change over time. However the simpler procedure of comparing weight and height centiles (eg a difference of two or three channel widths) is a poor measure of weight-for-height and should not be used.

Objective: To explore the relationships between height and (a) fat-free mass (FFM) and (b) fat mass (FM) in children in order to determine the optimum means of adjusting body composition for height., Design: Cross-sectional study., Subjects: Sixty-nine children aged 8 y., Measurements and Methods: Weight and height (HT) were measured, and total body water by deuterium dilution for estimation of fat-free mass and fat mass. The indices FFM/HT(2) and FM/HT(2) were calculated, as were the indices FFM/HT(p) and FM/HT(p) where P was selected in order to eliminate the correlation of these indices with height., Results: FFM was optimally adjusted for height by calculating FFM/HT(2). FM was optimally adjusted by calculating FM/HT(6). However, height accounted for <8% of the variation in FM/HT(2), indicating that the bias of this simpler index is small., Conclusions: Different adjustments of FFM and FM for height are possible, depending on the study design. The indices FFM/HT(2) and FM/HT(2) are appropriate for many purposes, and have the advantage of expressing both aspects of body composition in common units. However, in some scenarios a more sophisticated approach is required for evaluating body fatness.

Primary Objectives: The only reference centile curves currently available for body proportions of children in the UK were constructed more than 20 years ago by Tanner and Whitehouse. The current study was designed to produce up-to-date sitting height and subischial leg length centile curves for boys and girls in Southeast England., Research Design and Methods: A convenience sample of 1424 boys and 1208 girls aged under 25 years from Southeast England was measured by a single observer in 1995-1996. Using Cole's LMS method, centile curves were constructed for sitting height and subischial leg length, and the medians by age and sex were then scaled to sum to the corresponding median height of the British 1990 reference., Results: The new centile curves for boys and girls are presented. They differ significantly from those of Tanner and Whitehouse in leg length (boys p < 0.001; girls p < 0.01), but not in sitting height., Conclusions: The Tanner and Whitehouse reference curves for body segment length are not suitable for contemporary British children, whose legs are longer than they were a generation ago. It is proposed that the curves presented here be adopted provisionally as the new British reference.

Background: This is a study of the associations of adult leg and trunk length with early life height and weight, diet, socioeconomic circumstances, and health, and parental height, divorce and death., Method: The data used were collected in a longitudinal study of the health, development and ageing of a British national birth cohort (N = 2879 in this analysis) studied since birth in 1946. Multiple regression models were used to investigate the relationships., Results: Adult leg and trunk length were each positively associated with parental height, birthweight, and weight at 4 years. Leg length was associated positively with breastfeeding and energy intake at 4 years. Trunk length was associated negatively with serious illness in childhood and possibly also parental divorce, but not with the dietary data., Conclusion: Adult leg length is particularly sensitive to environmental factors and diet in early childhood because that is the period of most rapid leg growth. Trunk growth is faster than leg growth after infancy and before puberty, and may be associated with the effects of serious illness and parental separation because of the child's growing sensitivity to stressful circumstances, as well as the result of the biological effects of illness.

Objectives: Preterm infants are known to remain small during childhood. We previously found that evidence of neonatal metabolic bone disease was associated with reduced length at 18 months. We aimed to further investigate factors predicting childhood height and to test the hypothesis that evidence of early metabolic bone disease is associated with reduced later height., Study Design: A cohort of preterm infants was measured prospectively at 18 months (n = 765), 7. 5 to 8 years (n = 772), and 9 to 12 years of age (n = 503)., Results: Preterm infants remained short for their age and sex at all follow-ups. Later height was most strongly predicted by parental height and, at 9 to 12 years, by pubertal status. Neonatal factors associated with later height were birth weight SD score, maternal hypertension/toxemia, and a high peak plasma alkaline phosphatase during the neonatal period. After adjustment for these factors plus interim heights, height at 9 to 12 years was greatest in those who were tallest at 7.5 to 8 years, those who had shown the greatest increase in height percentile between 18 months and 7.5 to 8 years and, as expected, those who were pubertal, whereas children with a peak neonatal plasma alkaline phosphatase >1200 IU were significantly shorter., Conclusions: Childhood height in preterm infants is strongly influenced by genetic factors. However, biochemical evidence of metabolic bone disease during the neonatal period may have a long-term stunting effect persisting up to 12 years later, providing support for current practices that aim to prevent this condition.

Galton (Journal of the Anthropological Institute of Great Britain and Ireland, 15, 246-263, 1886) defined midparent height as the average of the two parental heights. An alternative is to average the parental heights after converting them to standard deviation scores (SDSs). The aim of the paper is to compare the two midparent height calculations, and to see if they explain the imputation procedure used by Galton to adjust for the difference in adult height between daughters and sons. He multiplied daughters' heights by 1.08 before averaging them with sons' heights. Using data from 17 national height references it is shown that this procedure is equivalent to averaging the height SDSs of the sons and daughters. It demonstrates that midparent height SDS obtained by averaging the height SDSs of the two parents is a valid alternative to conventional midparent height.

Since the 19th century there have been clearly documented secular trends to increasing adult height in most European countries, with current rates of 10-30 mm/decade. Over the same period menarcheal age has also fallen steeply, but has now stabilized at approximately 13 years and may be rising again. Height trends tend to be greater in childhood than in adulthood due to the associated advance in maturation, but no trends are apparent before the age of 2 years. In particular, birth-weight trends are small and different in shape from height trends. The adult height trend matches that at age 2 years, so that the increment in adult height has already been achieved by age 2 years. To try to identify factors relating to the secular trend, increased height gain in late infancy is hypothesized to be equivalent to a reduction in stunting, and stunting is thought to be caused by impaired growth in the long bones of the leg in later infancy. Leg growth may be regulated by the expression of growth-hormone receptors on the growth plates, which it is hypothesized are susceptible to the interaction between concurrent nutrition and the nominal growth rate set during pregnancy. The timing of menarche is also likely to be determined by some growth factor operating near the time of birth, which also affects later weight, but not height.

Objective: To develop a chart to identify non-familial short stature., Design: A height chart that adjusts for maternal, paternal, midparental, or sibling height based on the British 1990 height reference., Main Outcome Measure: Height between 2 and 9 years of age., Results: The chart identifies children whose height is below the familially adjusted 0.4th centile, assuming a correlation of 0.4 between child height standard deviation score (SDS) and familial height SDS. The adjustment can be for parents, either alone or together, or for a sibling aged 2-9 years. The chart identifies about 2 children/1,000 over and above the 4/1,000 identified by the unconditional 0.4th centile., Conclusion: The chart should be a useful addition to screening programmes for short stature.

Cross sectional data reporting the height, weight, and body mass index of UK patients with cystic fibrosis are presented. During the first decade of life height and weight in patients with cystic fibrosis are maintained at about 0.5 SD below those of the general population, which reflects an improvement over earlier published observations. Postpubertal stature and weight maintenance in the cystic fibrosis population still show substantial deficits which may be related to treatment.

In this study the growth curves of 229 children (145 boys, 84 girls ) with idiopathic short stature (ISS) were analysed in three ways: (1) we compared the results of longitudinal modelling by means of Karlberg's ICP model with those of a cross-sectional analysis; (2) we studied to what extent an individual changes his/her height standard deviation score (SDS) position during childhood; and (3) we constructed height velocity curves for children with ISS using Cole's LMS method, and compared these with the British references. During childhood the difference between the average longitudinal and the cross-sectional height curves was less than 1 cm and the spread was almost identical. The average change in height SDS during childhood was not different from zero, indicating that in general growth of children with ISS was well canalized. The individual change in height SDS position during childhood was within 0.6 SDS for a follow-up of 1 year, increasing to 1.9 SDS for a follow-up of 7 years. During childhood mean height velocity was about 1 cm/year lower than that of the British reference. With respect to the pubertal growth spurt the maximum height velocity took place 1 year later, and was 0.6 cm/year lower than the British reference in boys as well as girls. We conclude that spontaneous growth of children with ISS adequately described by a cross-sectional curve.

The purpose of this study was to assess relations among height, weight, and body mass index (BMI) at different ages from childhood to adulthood, and to examine long-term relations among timing of puberty, height, and BMI. Longitudinal data from the 1958 British birth cohort (all children born between March 3rd and 9th, 1958) were used. Height and weight were measured at ages 7, 11, 16, 23 (self-reported), and 33 y; pubertal status was assessed at ages 11 and 16 y. Data for 5700 females and 5512 males were analyzed. Adult height was well predicted from childhood, with strong correlations (r = 0.7 for both sexes) between height at ages 7 and 33 y. Correlations for BMI were weaker, especially between childhood and early adulthood (r = 0.33 for males and 0.37 for females, ages 7 and 33 y), although they increased with increasing age. Although the fattest children had the highest risks of adult obesity, most obese adults had not been fat at earlier ages: only 17% and 18% of obese 33-y-old men and women, respectively, had been fat at age 7 y. A strong and evenly graded association was found between timing of puberty and BMI, with higher mean BMIs for the earlier maturers at ages 7-33 y. The moderate prediction of adult BMI in this large and unselected sample suggests that although the prevention of childhood fatness may be desirable, most obese adults could not be identified from their childhood BMI, and hence, preventive strategies need to be population-based.

This study compares how effectively the ponderal index and the body mass index adjust birthweight for length at different gestations, and derives an improved index suitable for all gestations. The study was a cross-sectional survey, in a London teaching hospital, using a total of 999 neonates of 33 weeks gestation or later. Main outcome measures were the ponderal index (birthweight/length3), body mass index (birthweight/length2), and Benn index (birthweight/length(n)), where the length power n varies with gestation and is estimated by log-log regression. Results showed that up to 39 weeks gestation, the ponderal index is uncorrelated with length and so is a good index of birthweight for length. Past 39 weeks gestation, the ponderal index is negatively correlated with length, while the body mass index is uncorrelated, so that the body mass index is better. Neither index is optimal at all gestations. Deriving the Benn index (birthweight/length(n)) for each week of gestation, choosing n to make the index uncorrelated with length, shows that n falls steadily and very significantly (p < 0.0001) with increasing gestation. This in turn means that predicted birthweight for length depends on gestation: for a neonate 48 cm long, predicted birthweight varies from 2485 g at 34 weeks to 3030 g at 43 weeks, a 20% range. However, for a 54 cm long infant, predicted birthweight is the same at all gestations. A Benn index where the value of n changes linearly with gestation is described. We conclude that the ponderal index is not appropriate for measuring intra-uterine malnutrition, as it fails to adjust for length at all gestations. No other index of birthweight/length(n) with constant n is any better, as different gestations require different indices. Birthweight predicted from an infant's length depends on the infant's gestation. If, as Barker proposes, thinness at birth assessed by birthweight for length is used to predict later health status, more account needs to be taken of the complex relationship between birthweight, length and gestation.

Aim: To provide a simple method for assessing centile change based on the British 1990 growth reference., Statistical Method: The change in SD score over a period of time has SD square root of 2(1-r), where r is the correlation between the first and second SD score. This leads to an SD score for centile change., Data: Annual height measurements from 2 to 9 years for 318 children from the French longitudinal growth study., Results: The correlations between heights at different ages are higher for shorter measurement intervals and at older ages. The chance of a child's height centile falling one centile band width is correspondingly smaller for shorter measurement intervals and at older ages. An increase in height measurement error reduces the correlations and dramatically increases the chances of centile crossing., Conclusions: Quantitative height monitoring based on centile change is provided for whole year periods between 2 and 9 years of age. Effective monitoring requires the measurement error to be as small as possible.

Body size is an important predictor of bone mineral content (BMC) at various anatomical sites but the influence of relative body proportions on BMC has previously been little studied. Using single- and dual-photon absorptiometry, we measured BMC at the distal and midshaft of the radius, the neck of femur, and the lumbar spine in 190 rural West African women aged 45-84 years. After regression adjustment for age, bone width and weight, sitting height and standing height were not separate significant determinants of BMC, except at the lumbar spine (standing height, p < 0.05). However, the ratio of sitting:standing height was a significant determinant of BMC at the neck of femur and lumbar spine, but not the midshaft or distal radius. The fact that sitting:standing height ratio is a positive predictor for BMC at hip and lumbar spine may reflect a higher peak bone mass or selective conservation of mineral in weight-bearing bones in subjects with a proportionately longer torso. We do not know whether the relationship is racially determined but we recommend that this simple combination of measurements be used in further studies in subjects of all races.

Swedish population reference standards for height, weight and body mass index (BMI) attained at 6 to 16 years (girls) or 19 years (boys) are presented. Data were obtained from two independent nationwide samples of Swedish children; one (740 children) born in 1955, the other (2907 children) born in 1967. The weights of the children born in 1955 were adjusted to equal those born in 1967; heights did not differ. These reference standards refer therefore to Swedish children born at around 1970. The observations were fitted by the power transformation, or L, M, S method of Cole and Green. Weights and BMIs were thus normalized and valid SD scores for individuals obtained. Centile charts are given for clinical use. The means of the present, nationwide standards were 1-2 cm and 1-2 kg greater than those of the Solna-based standards currently in use.

The current reference curves of stature and weight for the UK were first published in 1966 and have been used ever since despite increasing concern that they may not adequately describe the growth of present day British children. Using current data from seven sources new reference curves have been estimated from birth to 20 years for children in 1990. The great majority of the data are nationally representative. The analysis used Cole's LMS method and has produced efficient estimates of the conventional centiles and gives a good fit to the data. These curves differ from the currently used curves at key ages for both stature and weight. In view of the concerns expressed about the current curves and the differences between them and the new curves, it is proposed that the curves presented here should be adopted as the new UK reference curves.

Weight-for-height standards in children are usually constructed on the basis that the expected weight for a given height does not depend on age, an assumption which is unjustified. The present paper investigates regression standards of age-standardized weight for age-standardized height, the standardization being achieved by expressing weight and height as fractions of the 50th centile for age from a suitable growth standard. The precise choice of standard is not critical. Data on 4631 children from five different countries, exhibiting a wide spectrum of growth status, show that throughout childhood until puberty, the following ratio is appropriate as a simple and convenient index of weight-for-height: age-standardized weight/(age-standardized height)2. During puberty a larger power than 2 is required, so the index as specified is inappropriate. Approximate values for the distribution centiles of the index are suggested. The index may be used to assess degree of malnutrition or obesity, for individuals or groups seen on a single occasion. A slide-rule is described which calculates the index directly, given the child's sex, age, height and weight.

The protein-energy malnutrition classification schemes of Waterlow and McLaren, although similar in other respects, assess the weight-for-height of children in quite different ways. The drawbacks of their two methods are described, and an alternative method is presented which overcomes them. The new index is called weight/height2-for-age, and consists of the ratio weight/height2 expressed as a percentage of the same ratio for a reference child of the same age. Although the index is not age independent, it is insensitive to all but the grossest errors in age for children over 12 months old. The index is equally appropriate for the assessment of obesity. A slide-rule based on the Tanner standard is available to do the calculation.

The American National Center for Health Statistics (NCHS) and Dutch national height growth standards, unlike previous standards, allowed for skewness when fitting the centile curves. The LMS method (Cole 1988) is a way of summarizing growth standards which monitors the changing skewness of the distribution during childhood. It does so by calculating the Box-Cox power needed to transform the data to normality at each age, and displaying the results as a smooth curve of power plotted against age. Applying the LMS method to the NCHS and Dutch standards highlights the nature of the changing skewness of height during childhood, and particularly during puberty. Taken in conjunction with curves for the mean and coefficient of variation of height plotted against age, the power curve allows the original centiles to be reconstructed to high accuracy. This provides further evidence that the LMS method is a powerful and compact technique for deriving and presenting growth standards.

Data from three American Health Examination Surveys and 11 other published studies were used to investigate the weight-for-height index W/Hp, adjusted for age and sex by expressing it as a fraction of the same ratio for an NCHS standard child. The appropriate power of height p was determined by regressing log weight-for-age on log height-for-age, giving an index of relative weight which is highly correlated with weight but uncorrelated with height for age. The optimal value of p was 2 in pre-school children, but it increased gradually to 3 at age 11 and fell back to 2 after puberty. The largest value of p occurred 18 months earlier in girls than in boys, and the pattern was the same for white and black children. The trend was summarized by the formula: p = 2 + exp [-0.5 (age - 11)2]. The index thus provides a compact way of adjusting weight for height and age throughout childhood, using standards of weight and height for age and sex. During puberty, W/Hp was found to be related to maturity as measured by Greulich-Pyle bone age. Each year's advancement relative to chronological age was associated with an increase of up to 5% in relative weight, adjusted for height and age. This maturity effect was shown to be the cause of the rise in the value of p early in puberty, so that after adjusting for it the value of p remained close to 2 throughout childhood. Thus the index W/H2 is appropriate for preschool children and adults, but early in puberty it tends to assess tall or physically advanced children as being overweight. This bias can be avoided by using instead the more general index, where the precise power of height is a function of the child's age.