References for growth and pubertal development from birth to 21 years in Flanders, Belgium.

BACKGROUND: Due to the secular trend in length and height, growth references need to be updated regularly. Reference charts that were until recently used in Belgium are based on samples collected more than 30 years ago, and references for body mass index (BMI) and pubertal development have not been established before. AIMS: To establish contemporary cross-sectional reference charts for height, weight, BMI, head circumference, and pubertal development from birth to 21 years of age, based on a representative sample of children from Flanders, Belgium. SUBJECTS AND METHODS: 15 989 healthy subjects of Belgian origin, 0-25 years of age, were measured in 2002-2004. Growth curves were fitted with the LMS method, and percentiles for the pubertal development were estimated with generalized additive models on status quo data from 8690 subjects aged 6-22 years of age. RESULTS: A positive secular trend in height and weight is observed in children above 5 years of age. Adult median height has increased by 1.2 cm/decade in boys and 0.8 cm/decade in girls; median weight by 0.9 kg/decade in boys, and 1.0 kg/decade in girls, and the weight distribution became more skewed. The BMI curve is comparable to that of other populations, except for higher percentiles. This reflects the increasing prevalence of overweight and obesity. Median age at menarche (13.0 years) has not advanced any more over the past 50 years. Median ages at menarche and B2 in girls and G2 or T4 in boys are comparable to other West European estimates, but approximately 10% enter G2/T4 before 9 years of age. CONCLUSIONS: The ongoing secular trend in height and weight makes growth charts previously used in Belgium obsolete. New representative charts for growth and pubertal development are introduced. For weight monitoring, it is advised that the now-available BMI growth charts are used.

[Body mass index charts of Algerian children and adolescents (6-18 years)]. / Courbes de l'indice de masse corporelle d'enfants et adolescents algériens (6­18 ans).

The body mass index (BMI) is widely accepted as a measure of overweight and obesity in children. There are no BMI reference charts for Algerian children and adolescents. The purpose of this study was to construct BMI percentile curves appropriate for children aged 6-18 years in Algeria. The weight and height of 7772 (54.9% girls) healthy schoolchildren from Constantine (eastern Algeria) were measured in 2008/2009. Weight and height for age curves based on the same sample were published previously. The BMI for age percentile curves were estimated in girls and boys separately using the LMS smoothing method. In both sexes, the median BMI increased with age. Girls had lower BMI values than boys before the age of 10 years but they were higher after this age until 18 years of age. Within the study population, the prevalence of overweight (including obesity) and obesity in girls and boys together was 13.7% and 3.0%, respectively, according to the International Obesity Task Force (IOTF) and 16.9% and 4.9% according to the World Health Organization (WHO) (2007). The median BMI curves of Algerian girls and boys were generally lower than those observed in other Arab countries. Compared with other references, the median BMI values of girls were lower than those of a Belgian Flemish population and WHO 2007 until 14 years of age and higher than the French reference between 7 and 18 years of age. The BMI values of Algerian boys were close to the Belgian (Flemish population), French and WHO 2007 references between 6 and 9 years of age and generally lower thereafter. These BMI curves are complementary to the height and weight charts published previously for the assessment of growth in children and adolescents. They were developed according to international guidelines and could serve as a national reference. They could be used as a complement to the 0- to 5-year-old WHO 2006 standards.

[Weight and height local growth charts of Algerian children and adolescents (6-18 years of age)]. / Courbes de poids et de taille d'enfants et adolescents algériens âgés de 6 à 18 ans.

Measurements of height and weight provide important information on growth and development, puberty, and nutritional status in children and adolescents. The aim of this study was to develop contemporary reference growth centiles for Algerian children and adolescents (6-18 years of age). A cross-sectional growth survey was conducted in government schools on 7772 healthy schoolchildren (45.1% boys and 54.9% girls) aged 6-18 years in Constantine (eastern Algeria) in 2008. Height and weight were measured with portable stadiometers and calibrated scales, respectively. Smooth reference curves of height and weight were estimated with the LMS method. These height and weight curves are presented together with local data from Arab countries and with the growth references of France, Belgium (Flanders), and the World Health Organization (WHO) 2007. In girls, median height and weight increased until 16 and 17 years of age, respectively, whereas in boys, they increased through age 18 years. Between ages 11 and 13 years (puberty), girls were taller and heavier than boys. After puberty, boys became taller than girls, by up to 13 cm by the age of 18 years. Median height and weight of Algerian boys and girls were generally intermediate between those observed in other Arab countries. They were higher than the French reference values up to the age of 13 years and lower than Belgian and WHO reference values at all ages. The present study provides Algerian height- and weight-for-age growth charts, which should be recommended as a national reference for monitoring growth and development in children and adolescents.

Influence of hOGG1, XRCC1 and XRCC3 genotypes on biomarkers of genotoxicity in workers exposed to cobalt or hard metal dusts.

Identification of genetic polymorphisms responsible for reduced DNA repair capacity may allow better cancer prevention. We examined whether variations in genes involved in base-excision (hOGG1, XRCC1) and double strand break (XRCC3) DNA repair contribute to inter-individual differences in genotoxic effects induced in the lymphocytes of 21 cobalt (Co) exposed, 26 hard metal (WC-Co) exposed and 26 matched control male workers. Genotyping was performed by PCR-RFLP. DNA single strand breaks and alkali-labile sites were measured by the alkaline Comet assay. Chromosomal rearrangements resulting from chromosome loss or acentric fragments were assessed as micronucleated mononucleates (MNMC) and binucleates (MNCB) with the cytokinesis-block micronucleus test. Urinary 8-hydroxydeoxyguanosine (8-OHdG) levels were used as an indicator of systemic oxidative DNA damage. A significantly higher frequency of MNMC was observed in WC-Co exposed workers with variant hOGG1(326) genotype. Multivariate analysis performed with genotypes, age, exposure status, type of plant, smoking and their interaction terms as independent variables indicated that MNMC and Comet tail DNA (TD) were influenced by genetic polymorphisms. In the exposed and total populations, workers variant for both XRCC3 and hOGG1 had elevated MNMC frequencies. Further studies will demonstrate whether genotyping for hOGG1 and XRCC3 polymorphisms is useful for a better individual monitoring of workers.

Determinants of growth in body length from birth to 6 years of age: A longitudinal study of Lublin children.

The effect of determinants of growth in body length from birth to 6 years of age were studied in a longitudinal sample of 59 male and 70 female infants from Lublin, Poland. Structural equation modeling (SEM) was used to study the effects of gender of the child, occupation of the parents, the educational level of the parents, per capita income, the stature of the parents, and the weight of the mother on body length at birth and at 1, 2, 3, and 6 years of age. Significant sex differences in length were observed at birth and during the first 2 years of postnatal life, but not in the period between 3 and 6 years of age. Socioeconomic status (SES), expressed as a latent variable in the SEM, was not related to body length at birth but was significantly related to body length during infancy and, to a lesser extent, to body length during childhood. Paternal stature was not related to body length at birth and during infancy, but was significantly related to body length from 3 years onwards. Maternal stature was significantly related to body length at birth and at 1 year of age, but not thereafter, while maternal weight was significantly related to body length at birth only. © 1996 Wiley-Liss, Inc.

Height velocity in Argentinean girls with Turner's syndrome.

Height velocities from birth to maturity derived from 1,049 height increments measured over intervals 0.85-1.15 years were studied from a sample of 187 patients with Turner's syndrome (TS) diagnosed on the basis of karyotype. Length of follow up in each girl varied from 1.0 to 11.0 years. Cross-sectional analysis showed a relatively stable growth velocity during pubertal ages. However, longitudinal analysis of individual growth curves showed the existence of a small growth spurt in 37 out of 47 girls with available data during pubertal years. Mean peak height velocity (PHV) of this spurt was 5.7 cm/year, SD 1.34; mean age at PHV was 12.66 years, SD 1.70. Selected percentiles were calculated using the least mean squares (LMS) method. Results show that a small growth spurt in girls with TS may be more frequent than previously thought.

Mathematical models for the study of individual growth patterns.

The analysis of longitudinal growth data requires specific methodological approaches. One of the main goals of longitudinal growth studies is to establish individual growth patterns and to estimate, so-called, biological parameters of the growth curve, such as the timing and intensity of the adolescent growth spurt, for example. These features are providing us with information about the shape of the growth curve, rather than telling us what size is attained at a particular age. A basic technique to establish the continuous growth process from a set of discrete measurements of size in function of age is provided by curve fitting. Various models have been proposed to achieve this goal. They can mainly be subdivided into nonstructural and structural models. This paper deals with a description of some of the most commonly used models in the analysis of human growth data, emphasizing on their applicability in certain age periods and on the merits and limitation of the various approaches. Attention is also paid to a special type of nonstructural models based on longitudinal principal components analysis.

Secular changes in growth and maturation: an update.

Secular changes in growth and maturation in recent decades have been reviewed for various populations. The secular increase in attained height during the growth period is continuing in most countries, but has slowed down. The increase in adult stature over the past decades has varied between 0.3 and 3.0 cm/decade. The secular trend in the tempo of growth (earlier menarche and peak height velocity, and shortening of the growth cycle) has come to a halt in some populations, but is continuing or has been reversed in others. The secular trend in attained height and in the tempo of growth is usually more pronounced in children from low socioeconomic backgrounds, in those with poorly educated parents or in those from rural areas. It is concluded that updates of growth standards are required in all populations. More marked secular changes appear to occur in the lower height centiles, which may have direct implications on the future definition of 'short stature' in a population.

Growth of Belgian and Norwegian children compared to the WHO growth standards: prevalence below -2 and above +2 SD and the effect of breastfeeding.

BACKGROUND: New national growth references have been published in Belgium and Norway. The WHO recommends universal use of their 2006 Child Growth Standards based on data from breastfed children. OBJECTIVE: To compare the growth of Belgian and Norwegian children with the WHO standards. PARTICIPANTS: 6985 children 0-5 years of age from Belgium and Norway. DESIGN: Proportion of children below -2 SD and above +2 SD of the WHO standards was calculated for length/height, weight, body mass index and head circumference. Average SD scores of exclusively breastfed children of non-smoking mothers were compared with national reference data and with the WHO standards. RESULTS: Generally, the number of Belgian and Norwegian children below -2 SD lines of the WHO standards was lower and above +2 SD higher than expected. The largest differences were for head circumference (0.97% Belgian and 0.18% Norwegian children below -2 SD, 6.55% Belgian and 6.40% Norwegian children above +2 SD) and the smallest for length/height (1.25% Belgian and 1.43% Norwegian children below -2 SD, 3.47% Belgian and 2.81% Norwegian children above +2 SD). The growth pattern of breastfed children of non-smoking mothers was in both countries more alike the local national growth references than the WHO standards. CONCLUSIONS: There are significant deviations in the proportion of children outside normal limits (±2 SD) of the WHO standards. This was true for all children, including those who were exclusively breastfed. Hence, adoption of the WHO growth charts could have consequences for clinical decision-making. These findings advocate the use of national references in Belgium and Norway, also for breastfed children.

Multifactorial analysis of a mixed-longitudinal sample of Indian siblings: Age and sex effects on heritability.

The aim of the present study was to examine the heritability of 11 traits in a mixed-longitudinal sample of Indian siblings, and to determine whether heritability estimates vary during the growth period and whether they are influenced by sex. The sample consisted of 245 brothers and 213 sisters from 138 nuclear families living in a semi-urban area in Kolkata, India. The age ranged between 5 and 19 years. The traits were standardised for age and sex using standard deviation scores (SDS) produced by the LMS method (Cole, T.J., 1988. Fitting smoothed centile curves to reference data. J. R. Stat. Soc. A 151, 385-418). The standard deviation scores were analysed by PCA. The two factors with eigenvalues above 1 explained 77.3% of the variance; they showed a high level of pleiotropism present among the studied traits and represented body lengths (PC1) and body weight and breadths (PC2). The heritability between all types of siblings (irrespective of sex) for the PC1 and PC2 was estimated. The heritability between various pairs of siblings showed variations along the whole ontogenetic period studied. During the childhood and pre-pubertal period, heritability between brothers, brother-sister pairs and any sibling pairs was mostly constant, with small and non-significant variations. All the pairs showed the lowest degree of heritability during puberty for PC1 but not for PC2, with significant changes of heritability estimates between adolescence and adulthood, in most of the analysed sibling pairs and in both PC factors. The highest heritability was generally observed at the end of the examined growth period in all pairs. A significant effect of sex on heritability was only detected for PC2 at 11 years of age.

Heritability variations of morphometric traits in West Bengal (India) children aged 4-19 years: a mixed-longitudinal growth study.

BACKGROUND: Longitudinal and semi-longitudinal growth studies on siblings reflecting heritability changes during growth are very scarce. Moreover, studies of variables other than height, weight and BMI are virtually non-existent. AIM: The study compared changes in the heritability of six body lengths, four body breadths, and three indices between ages 4 and 19 years on the basis of a mixed-longitudinal sample of siblings, and examined whether heritability estimates change during the growth period. The data consisted of 238 brothers and 214 sisters from 134 middle-class nuclear families living in Kolkata (India). The analysis of sibling correlation was performed by maximum likelihood. The age-related patterns of heritabilities of the various traits were described by a cubic spline. RESULTS: The heritability was very high and significant in most traits, and at all considered ages. Mean heritability in the 10 morphometric traits was 69.3%, which was higher than the heritability values for the three indices. CONCLUSIONS: These results confirmed the existence of age-related trends in heritability of the considered morphometric traits. The sharp decline of the heritabilities at adolescence in most of the morphometric traits, and the acromio-iliac index in particular, may be due to the large inter-individual variation in the age at which the adolescent growth spurt is reached in both sexes.

Overweight and obesity in Norwegian children: secular trends in weight-for-height and skinfolds.

AIM: The prevalence of overweight and obesity in paediatric populations has been rapidly increasing in many countries over the past decades. The aims of the present study were to provide new data on weight-for-height and skinfolds, and to compare these to growth references for children between 3 and 17 years, collected in the same city between 1971 and 1974. MATERIAL: The present study is based on cross-sectional data of 4115 children (2086 boys and 2029 girls) aged 4-15 years measured in 2003-6. RESULTS: Overall, 18.0% of the boys and 20.1% of the girls were above the 90th weight-for-height percentile of the 1971-1974 references, 8.0% and 7.2% were above the 97.5th percentile, indicating an upward shift in weight-for-height. An even more prominent increase was observed for skinfold thicknesses; for triceps skinfolds about 30% of the boys and 28% of the girls were above the 90th percentile of the 1971-1974 references, and corresponding values for subscapular skinfolds were 26.5% and 25.9%. Using international cut-off values for body mass index, the overall prevalence of overweight and obesity was 12.5% and 2.1% in boys, and 14.8% and 2.9% in girls. CONCLUSIONS: Our study has demonstrated a significant increase in weight-for-height in Norwegian children over the last 30 years, and that these changes are caused by an increase in fat tissue, as shown by skinfold measurements. The current prevalence of overweight and obesity is comparable to recent estimates from most Western and Northern European countries.

Age trends of sibling resemblance for height, weight and BMI during growth in a mixed longitudinal sample from Sarsuna-Barisha, India.

BACKGROUND: Even though some studies have considered that sibling resemblance remains constant throughout the life cycle, several investigations emphasize the importance of age and its interactions with genetic and environmental factors in determining sibling similarity in several bodily traits. In fact, the study of age changes in familial resemblance is of great importance for the analysis of certain sources of variation observed in growth processes. AIM: The study examined sibling resemblance for height, weight and body mass index (BMI) in a mixed longitudinal sample from West Bengal, ages 2-19 years, in order to analyse the variations with age of the sibling resemblance for these phenotypes during growth. SAMPLE AND METHODS: Two hundred and forty-five brothers and 213 sisters from 138 middle-class nuclear families living in a semi-urban area of South Kolkata, India were analysed. The analysis of sibling resemblance was performed through correlations estimated by the maximum-likelihood method. The patterns of different trends of sibling resemblance with age were examined by fitting a cubic non-linear regression to the observed correlations. RESULTS: The results show clear variations with age in the sibling resemblance for the traits height and weight, though to a lesser extent for BMI. In general, we found the highest correlation values during the period of infancy, a remarkable decrease during puberty, and a trend of increase towards the end of the growth cycle. CONCLUSION: The study confirms the effect of age on the degree of similarity among siblings for height, weight and BMI in the sample. The sharp decline of correlation at adolescence can be interpreted in terms of the individual variation in age of reaching the adolescent growth spurt.

Growth in weight of African babies, aged 0-24 months, living in a rural area at the Lake Tumba, Zaire.

Weight charts in two rural African populations (Ntomba Oto and Twa) have been constructed on the basis of 26,330 measurements of weight of babies aged from birth to 24 months. Centile lines were produced by fitting the Jenss-Bayley growth curve to the respective centile values calculated at each age. The average patterns of increase in weight in boys and girls in the two populations are compared with those in other populations.

Skeletal maturity at onset of the adolescent growth spurt and at peak velocity for growth in height: a threshold effect?

In 191 Polish boys of the Wroclaw Growth Study, the relationship between skeletal age and chronological age was examined at the onset of the adolescent growth spurt (take-off) and at peak velocity of height growth (PHV). It was found that, at PHV, skeletal age is markedly less variable than is chronological age, but at take-off no such reduction in variability is visible. The following interpretation of this finding is proposed. The onset of the spurt depends, ultimately, upon some maturational processes going on in the hypothalamus and shows little relationship with the advancement of the long bones at that time. Therefore, the spurt can begin at any level of skeletal maturity within the range normally observed at the chronological age at which it happens to begin in the individual. Peak height velocity, on the other hand, is reached when skeletal maturity is sufficiently advanced for testosterone to change its influence upon the bones from one which consists in stimulating cartilage growth to one which consists in stimulating epiphyseal fusion. Therefore, PHV is bound to occur within a range of skeletal maturity much more restricted than that within which take-off can occur.

The pattern of growth and growth retardation of patients with hypophosphataemic vitamin D-resistant rickets: a longitudinal study.

Growth in height of 16 patients (5 boys and 11 girls) with hypophosphataemic rickets (HR) was studied in a longitudinal survey. The data shortly before and during puberty were analysed on the basis of Preece Baines curves, fitted to the original data; for the analysis at the age of 5 years, the original data were used. It appeared that the overall shape of the individual and average growth pattern could be adequately described by the Preece Baines method. The results further showed that from the age of 5 years onwards, average height was approximately two standard deviations below the normal mean for Dutch children. The patients showed a normal pubertal growth spurt which was, in general, insufficient to restore the growth retardation already established before adolescence. The four children who did show catch-up growth between the age of 5 years and adulthood had minimal rachitic lesions. The greater impact of the disease on growth in early childhood than on adolescent growth could be explained by the fact that HR mainly affects the growth of the legs, the major contributor to body size in early childhood. Finally, it was found that the difference between bone age, as determined by the Tanner Whitehouse (TW2)-method, and chronological age was not significant and the adult height in all patients except two could be adequately predicted from bone age and height.

Maturational delay and temporal growth retardation in asthmatic boys.

Growth in height, bone age, and sexual maturation have been studied in asthmatic boys 2 to 20 yr of age. The mean pattern of growth in height has been analyzed mixed-longitudinally in 531 patients (1,754 measures) and seemed to be determined by a delay in physiologic maturation. The asthmatic boys' growth in height showed no retardation during infancy, a small but consistent retardation during childhood, a more pronounced delay at adolescence, and a catch-up growth toward adulthood. The mean adolescent growth spurt is delayed by about 1.3 yr. Bone age has been analyzed mixed-longitudinally in a subsample of 370 patients (660 observations) and showed a slight retardation at all ages between 6 and 13 yr. Development of pubic hair of 91 subjects analyzed cross-sectionally was definitely retarded when compared to adequate reference data. Evidence was given that factors secondary to the asthmatic syndrome are involved in the retardation of growth and development.

Longitudinal study of growth of African babies: an analysis of seasonal variations in the average growth rate and the effects of infectious diseases on individual and average growth patterns.

The aim of the present study is to produce standards of weight for age and to analyse the effects of seasonal variation and of infectious disease on the rate of growth in weight of Central African babies. The study is based on longitudinal data of 4030 babies, aged 0-4 years, living in the North Western tropical forests of Zaire. The growth rate in weight shows a cyclic pattern which appears to be synchronized with the alterations of rainy and dry seasons, the rainy seasons slowing down the growth velocity below average. The interactions of genetic and nutritional factors are discussed. Infectious diseases such as measles and whooping cough tend to slow down growth in varying degrees. The effects were studied in terms of loss in weight and the amount of time needed to fully catch-up.