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Bláha P.*, Vignerová J.** *Faculty of Science, Charles University, Prague National Institute of Public Health Czech Republic. 6th Nationwide Anthropological Survey of Children and Adolescents 2001.
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Bláha P.*, Vignerová J.** *Faculty of Science, Charles University, Prague National Institute of Public Health Czech Republic 6th Nationwide Anthropological Survey of Children and Adolescents 2001
FENOTYP OF AN INDIVIDUAL =GENETIC FACTORS + ENVIRONMENTAL FACTORS + INTERACTION BETWEEN GENETIC AND ENVIRONMENTAL FACTORS FAMILY ENVIRONMENT SES • 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.). PHYSICAL ENVIRONMENT STRESS HEALTH, GROWTH Flinn M.V., England B.G., American Journal of Physical Anthropology, 1997
Material I. • 1895: Measurements of 100.000 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. • 1800-1809: Mean heights and s.d. in military boarding-school children born between 1800-1809 (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. 33 - 48.)
Material I: NATIONWIDE ANTHROPOLOGICAL SURVEYS IN CR • Every ten years - 1951, 1961, 1971, 1981, 1991, 2001 • Number of children per survey: • 80.000 – 100.000 • (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 2001. • 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.
Z-SCORE ACCORDING WHO REFERENCE VALUES Height BOYS GIRLS Adult height: 1951 - 172.4 (s.d. 6.6) 2001 - 180.4 (s.d. 7.0) dif. 8.0 cm Adult height: 1951 - 161.0 (s.d. 5.6) 2001 - 167.2 (s.d. 6.4) dif. 6.1 cm
Z-SCORE ACCORDING WHO REFERENCE VALUES Weight BOYS GIRLS
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 cm 3400 g Girls: 49.7 cm 3270 g The secular trend of height appears significant from the category of two years olds onwards. MEAN BIRTH LENGTH AND WEIGHT
SECULAR TREND OF HEIGHT Growth curves
HEIGHT AND WEIGHT Comparison of age • In 1895it 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. • 1951 – 1.5years later • 1971 – 0.8years later • 1991 – 0.2 years later • The same applies to today’s 10 and 11 year old children Mean values of height and weight of boys and girls 9 year olds - in 2001
GROWTH VELOCITY OF THE HEIGHT • (cm per year) • Longitudinal studies cm 11,15 • A 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 1975 1995 Girls 11.5 11.1 Boys 13.6 13.3 • The time shift between boys and girls in the onset of adolescent growth spurt is almost 2 years. 7 7,16 13,32 6 7,87 5 4 boys girls 3 6 8 10 12 14 16 Age years
AGE OF MENARCHE AND VOICE-BREAKING 1991, 2001 Number: GIRLS: 12.837 BOYS: 9.645 Mean age of menarche: (50 % YES, 50 % NO) 1991: 13.00 years 2001: 13.01 years Mean age of voice-breaking: 1991: 14.50 years 2001: 13.84 years Corresponds with shifting of secular trend of height 0.01 y. 0.66 y. Logistic regression
AGE OF ADIPOSITY REBOUNDMethod • Age of adiposity rebound was defined as the local minimumposition of the fitted BMI curve.
AGE OF ADIPOSITY REBOUND Nationwide Anthropological Surveys BOYS GIRLS 1.3 1.2 Results for 50th centile, for higher centiles in the earlier age, for lower centiles later
BMI EMPIRICAL CENTILE CHARTS 1951, 1991 BMI EMPIRICAL CENTILE CHARTS1951, 1991 BOYS GIRLS Adiposity rebound: in 1951 - 1.5 year later
WEIGHT-HEIGHT RATIO Empirical centile charts 1951, 2001 BOYS GIRLS
PERCENTAGE OF OVERWEIGHT AND OBESE CHILDREN Reference data: WHO and IOTF recommendationsAge 7 – 11 years Report of the International Obesity Task Force, 2004
PERCENTAGE OF INHABITANTSBY EDUCATIONAL LEVELin the Czech Republic Czech Statistics Yearbooks Socio-economic conditions in which the child grows up are to a considerabledegree affected by the level of education of his or her parents.
HEIGHT, WEIGHT-HEIGHT RATIOby parental educational levelSurvey 2001, age 7.00 - 8.99 years (n = 3478) – before growth spurt Z-score Weight-height ratio Z-score Height 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) Z-score: using WHO reference data
MEAN BODY HEIGHT BY SIZE OF THE COMMUNITY AGE 7.00 YEARS BOYS GIRLS cm cm 1 - village 2 - small cities 3 - large cities 4 - Prague Statisticaly significant differences in 1951 Not statisticaly significant differences in 2001
Abstract: T. J. Cole: The secular trend in human physical growth: a biological view. Economics &Human Biology, Vol. 1, Issue 2, June 2003, pp. 161-168 … 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 1960. • 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.