6th Nationwide Anthropological Survey of Children and Adolescents 2001 Bláha P.*, Vignerová J.** *Faculty of Science, Charles University, Prague National Institute of Public Health Czech Republic

Apart from genetic determinants, growth of an individual is to a great extent influenced by external factors (familly backround, socio-economics conditions of the society, health care system, social system etc.). FENOTYP OF AN INDIVIDUAL = FENOTYP OF AN INDIVIDUAL = GENETIC FACTORS + ENVIRONMENTAL FACTORS + INTERACTION BETWEEN GENETIC AND ENVIRONMENTAL FACTORS FAMILYENVIRONMENT HEALTH,GROWTH SES PHYSICALENVIRONMENT STRESS Flinn M.V., England B.G., American Journal of Physical Anthropology, 1997

Material I. 1895: Measurements of school children - Czech physician and anthropologist Matiegka (Matiegka J., 1927, Somatology of school children. Nakl. ČSAV a umění, Praha.) – He founded tradition of Nationwide Anthropological Surveys : Mean heights and s.d. in military boarding-school children born between (in Bohemia and Moravia), recorded in Vienna (Komlos J: Patterns of children’s growth in East-central Europe in the eighteenth century. Annals of Human Biology, 1986, Volume 13, No. 1, pp )‏

Material I: NATIONWIDE ANTHROPOLOGICAL SURVEYS IN CR Every ten years , 1961, 1971, 1981, 1991, 2001 Number of children per survey: – (3 to 5 % of the population of given age)‏ Age: 0 to 19 years Praha

NATIONWIDE ANTHROPOLOGICAL SURVEYS IN CR (1951 to 2001)‏ Preschool children: in clinics, by instructed health professionals, mainly paeditricians. School children: teachers, provided with detailed written instructions. Anthropological measurements: height, body weight, circumferences of the head, arm, waist and hip – Martin Saller method. Questionnaires for children: dietary habits, sports activity, TV watching and PC games. Questionnaires for parents: parental height, weight, educational level, number of children in the family, breastfeeding and health status of their child.

METHODS Original data available from : 1951, 1981, 1991 and For other surveys: sample sizes for each age group, average values and standard deviations are available, for 1895 only average values. We have used only these summary values for the growth curves construction. Weighted polynomial smoothing spline of 3rd order was used for construction of the growth curves of the height. Weights were proportional to sample sizes at the particular time point. Its first derivative was then computed to obtain growth velocity.

BOYSGIRLS Z-SCORE ACCORDING WHO REFERENCE VALUES Height Adult height: (s.d. 6.6) (s.d. 7.0) dif. 8.0 cm Adult height: (s.d. 5.6) (s.d. 6.4) dif. 6.1 cm

BOYS GIRLS Z-SCORE ACCORDING WHO REFERENCE VALUES Weight

BIRTH WEIGHT- % in weight categories Boys Czech Helath Statistics Yearbooks

BIRTH WEIGHT - % in weight categories Girls Czech Helath Statistics Yearbooks

1951 – no data Since 1975 no changes Boys: 50.5 cmBoys: 50.5 cm 3400 g 3400 g Girls: 49.7 cmGirls: 49.7 cm 3270 g 3270 g MEAN BIRTH LENGTH AND WEIGHT The secular trend of height appears significant from the category of two years olds onwards.

SECULAR TREND OF HEIGHT Growth curves

3 years laterIn 1895 it was 3 years later (at 12 years) that boys and girls reached the same values of height and weight of today’s 9 year olds – 1.5 years later – 0.8 years later – 0.2 years later The same applies to today’s 10 and 11 year old children HEIGHT AND WEIGHT Comparison of age Mean values of height and weight of boys and girls 9 year olds - in 2001

boys girls 11,15 Age years 13,327,16 7,87 cm 4 months in girls and 3 months in boysA comparison of a study from 90s with one from 70s shows shift of growth spurt towards younger age categories: 4 months in girls and 3 months in boys Girls Boys The time shift between boys and girls in the onset of adolescent growth spurt is almost 2 years. GROWTH VELOCITY OF THE HEIGHT (cm per year)‏ Longitudinal studies

Number: GIRLS: BOYS: Mean age of menarche: (50 % YES, 50 % NO) ‏ 1991: years 2001: years Mean age of voice-breaking: 1991: years 2001: years Corresponds with shifting of secular trend of height AGE OF MENARCHE AND VOICE-BREAKING 1991, 2001 Logistic regression 0.01 y y.

AGE OF ADIPOSITY REBOUND Method Age of adiposity rebound was defined as the local minimum position of the fitted BMI curve.

AGE OF ADIPOSITY REBOUND Nationwide Anthropological Surveys BOYSGIRLS Results for 50th centile, for higher centiles in the earlier age, for lower centiles later

BMI EMPIRICAL CENTILE CHARTS 1951, 1991 BOYSGIRLS BMI EMPIRICAL CENTILE CHARTS 1951, 1991 Adiposity rebound: in year later

BOYSGIRLS WEIGHT-HEIGHT RATIO Empirical centile charts 1951, 2001

PERCENTAGE OF OVERWEIGHT AND OBESE CHILDREN Reference data: WHO and IOTF recommendations Age 7 – 11 years Report of the International Obesity Task Force, 2004

PERCENTAGE OF INHABITANTS BY EDUCATIONAL LEVEL in the Czech Republic Czech Statistics Yearbooks Socio-economic conditions in which the child grows up are to a considerable degree affected by the level of education of his or her parents.

HEIGHT, WEIGHT-HEIGHT RATIO by parental educational level Survey 2001, age years (n = 3478) – before growth spurt Parents’ education: 1. both lower level (basic and apprenticeship)‏ 2. one parent lower and one highter level 3. both parents higher level (high school, university)‏ Height Weight-height ratio Z-score Z-score: using WHO reference data

MEAN BODY HEIGHT BY SIZE OF THE COMMUNITY AGE 7.00 YEARS Statisticaly significant differences in 1951 Not statisticaly significant differences in 2001 BOYS GIRLS cm 1 - village 2 - small cities 3 - large cities 4 - Prague

T. J. Cole: The secular trend in human physical growth: a biological view. Abstract: T. J. Cole: The secular trend in human physical growth: a biological view. Economics &Human Biology, Vol. 1, Issue 2, June 2003, pp In Northern Europe, adult height has largely stabilised while weight continues to increase due to obesity … In Northern Europe, adult height has largely stabilised, and the age of menarche has also settled at around 13 years, while weight continues to increase due to obesity. The increase in height from one generation to the next occurs mainly in the first 2 years of life, due to increases in leg length. …

CONCLUSION The development of physical characteristics, in particular height and weight of children and adolescents, is a sensitive indicator for socio-economic conditions in which the children grow up and mature. Throughout the period of the 20th century - in line with improvements in socio-economic conditions - the physical height was increasing in all age categories. A shift in onset and peak of the growth spurt occured towards lower age categories. The period of its cessation, however, remains the same since The shift in growth spurt is linked with shift in the timing of onset of the sexual maturity. A shift also occured in the adiposity rebound. The proportion of children and adolescents with overweight and obesity is also increasing, although to a lesser degree than in other developed countries.