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Objective1.To understand the weight distribution and weight variation trends among Mongolian children and adolescents aged7to18from1985to2005by analyzing the weight survey results of Mongolian children and adolescents aged7to18in the year of1985,2000and2005;2.To establish reasonable and applicable weight reference values among Mongolian children and adolescents of different ages by using the ordinal clustering methods whose index is the weight of Mongolian children and adolescents aged7to18in2000, then using Mongolian students’physique research data in2005to verify the survey results;3.To provide a scientific basis for clinical diagnosis and developing intervention strategies and measures on school sanitation and child health care.MethodThe research data is from the national survey on Chinese students’fitness and health conducted among Mongolian students in Tongliao in1985,2000,2005. The number of effective subjects is5767in1985,5563in2000,2990in2005. With SPSS, this paper conducts a comparative analysis of the differences of weight between urban students and rural ones, boys and girls, students of different ages, and students in1985and2005to observe certain factor’s distribution, variation, differences and development trends. The paper uses the ordinal clustering methods to analyze the effective weight data in2000, then seeks the optimal segmentation, in other words, divides the optimal age groups, and counts the averages and standard deviation among each optimal age group so as to establish the weight reference range of each age group. After that this paper uses the effective weight data in2005to verify the extension rate of weight reference range.Results1.The weight of Mongolian children and adolescents aged7to18in1985,2000and2005has generally increased along with age, except that urban male students stop growing between17and18years old, which is in accordance with the general laws of growth and development. From1985to2005, the average weight of urban male students, rural male students, urban female students and rural female students aged7-18increases by5.44kg,4.52kg,3.83kg and3.17kg respectively. From1985to2000, the average weight of urban male students and rural male students increases by5.57kg and4.34kg, and the number of each age group is statistically significant; the average weight of urban female students increases by3.79kg, the number of each age group is statistically significant except that of urban female students aged17; the average weight of rural female students increases by3.29kg, the number between7to15years old is statistically significant. From2000to2005, the average weight of urban male students aged14decreases by3.43kg, that of rural male students aged11increases by2.46kg, and that of urban female students aged8increases by2.25kg, which are statistically significant, while the numbers of the rest age groups are not. The standard for rapid weight growth is3kg annually. During the20years, the rapid weight growth of urban and rural students had changed a lot. The average increase of weight from1985to2005is:urban boys> rural boys> urban girls> rural girls. Among10years, the weight growth among urban and rural students is greater than0.5kg. In the first15years, weight growth is significant, while in the later5years, the growth of weight slows down. In the year of1985,2000and2005, the largest weight growth among urban male students is13to14,13to14,12to13respectively; the largest weight growth among urban female students is11to12,11to12,10to11respectively; the largest weight growth among rural male students is14to15,12to13,12to13respectively; the largest weight growth among rural female students is12to13,11to12,10to11respectively. In the20years, the age of the largest weight growth among urban and rural students has advanced and the peak of growth spurt has advanced. The growth spurt period among urban students extends while that among rural students shortens. 2.The growth and development of children and adolescents is a continuous process. Considering their growth characteristics and changes in the growth spurt period, the paper divides the optimal age groups among male and female, among urban and rural Monglian students aged7to18based on weight. According to the optimal partitioning method, when the category number of urban and rural male students is5, and the category number of urban and rural female students is6, the minimum error function e[P (C, K)] ratio with next classification is smaller and in a rather stable state, and the ratios for urban male students, rural male students, urban female students and rural female students are1.4134,1.6111,1.3519and1.7210respectively. So it is better to divide urban and rural male students into5age groups, and the cut-points for urban male students are1,3,6,8,10, while the cut-points for rural male students are1,4,7,9,11, while it is better to divide urban and rural female students into6age groups, and their cut-points are1,3,5,6,8,10. While urban male students are divided into five age groups,7to8years old,9to11years old,12to13years old,14to15years old,16to18years old, rural male students are divided into five age groups:7to9years old,10to12years old,13to14years old,15to16years old,17to18years old. Urban and rural female students are divided into six age groups:7to8years old,9to10years old,11years old,12to13years old,14to15years old,16to18years old. Then the paper establishes32weight reference values for Monglian children and adolescents.3.The paper uses the effective data of Mongolian students in2005to verify the extension rates and finds that the minimum and maximum extension rates among urban male students are91.71%and97.69%respectively, and their average extension rate is94.23%; The minimum and maximum extension rates among rural male students are90.84%and100%respectively, and their average extension rate is95.25%; The minimum and maximum extension rates among urban female students are91.71%and98.44%respectively, and their average extension rate is94.23%; The minimum and maximum extension rates among rural female students are93.37%and98.44%respectively, and their average extension rate is95.47%; and all of them have reached the required standards (≥85%). ConclusionThe weight reference values which are established for Mongolian children and adolescents in this study highlight the characteristics of simplicity and practical applicability, fill the gap of Mongolian children and adolescents’weight standards of different age, have certain guidance over the prevention of malnutrition, overweight and obesity among Mongolian children and adolescents, and provide a scientific basis for developing strategies and measures on school sanitation and child health care.
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