Objective:To analyze the secular growth trends of the Chinese urban youth from 1979 to 2005,in order to make national intervention strategies and measures to improve their physical fitness and health.Methods:Subjects were sampled from 16 provincial-capital cities in China.They were all Han primary and secondary school students aged 7 to 18 years.The increments of stature,weight and BMI,and the increments per decade of these indicators at different stages were analyzed.Results:In recent 26 years,the overall increments were 6.5 and 4.7 cm for stature,and 8.9 and 5.2 kg for weight,for boys and girls,respectively.Swiftest rates were found in the period of 1985-1995,with the increments which were as high as 3.8 and 3.0 cm/decade for height,and 4.7 and 3.1 kg/decade for weight,for boys and girls respectively.These trends are still strong at present,without any tendency of going to the plateau.Advanced puberty plays the most contributing role in these trends,with the peak height rates being 2.4 cm/decade for girls at the age of 12 and 3.3 cm/decade for boys at the age of 14,respectively.The increments of adult height were 3.2 and 2.1 cm,while the rates were 1.2 and 0.8 cm/decade,for males and females,respectively.The distributing curves of BMI show an accelerating tendency of going to the right side,which suggests that the prevalence of childhood obesity is increasing rapidly.Conclusion:China is now experiencing an overall and positive secular trend,which is reflected not only by the accelerating physical growth in childhood,advanced puberty,and steady increments of adult height,but also by the dramatic changes of body shape.We should not only feel proud of the achievements of these secular growth changes and the active socioeconomic influences,but also pay much attention to their negative effects,especially those that may induce the dangers of hypertension,hyperglycemia,type 2 diabetes mellitus and other adulthood diseases,as well as the disease risks of metabolic syndrome that may even occur early in childhood and adolescence.

Objective:To analyze the current situation of age at menarche ( AAM) in Chinese ethnic minority girls aged 9 -18 years, and compare the AAM with that of Chinese Han girls from the same province or autonomous region .Methods:Probit analyses were used to calculate the AAM in various eth-nic minority groups of Chinese girls who participated in 2010 National Physical Fitness and Health Sur-veillance .The sample size of ethnic minority girls was 31 711, and the ethnic minorities were Mongolian , Hui, Tibetan, Uighur, Miao, Yi, Zhuang, Buyi, Korean, Dong, Yao, Bai, Tujia, Hani, Kazak, Dai, Li, Lisu, Wa, Shui, Dongxiang, Naxi, Kirgiz, Tu, Qiang and Sala.The local Han girls to compare with the AAM were also surveyed in 2010 National Physical Fitness and Health Surveillance .Results:In the 13-year-old group, the percentage of menarche in Sala was the lowest (32.17%), while that in Korean was the highest (93.23%).At the age of 18, 99.60%ethnic minority girls appeared menstruating .The AAM of the top 3 ethnic minority groups were Korean ( 11 .79 years ) , Mongolian ( 12 .44 years ) and Zhuang (12.52 years); and the last 3 ethnic minority groups were Dongxiang (14.36 years), Sala (14.32 years) and Shui (14.02 years).The AAM in Korean was 0.93 years earlier than that of the Han girls from Jilin province;the AAM in Mongolian was 0 .14 years earlier than that of the Han girls from Neimenggu autonomous region;the AAM in Naxi and Qiang was close to that of the Han girls in the same province (region) (P>0.05);and the AAM in Hui, Uighur, Miao, Yi, Zhuang, Buyi, Dong, Yao, Bai, Tujia, Hani, Kazak, Dai, Li, Lisu, Wa, Shui, Dongxiang, Kirgiz, Tu, and Sala was later than that of the Han girls in the same province ( region) .The cluster analysis indicated that the 26 ethnic mi-nority groups could be classified as three groups: Korean were classified into the earlier age group of AAM;Dongxiang, Sala, Uighur, Yi and Shui belonged to the later age group of AAM;and the other 20 ethnic minority groups were into the middle age group of AAM .Conclusion:There was a large variation among different ethnic minority groups in China .The AAM was earlier in Korean , and Mongolian , com-pared with the local Han girls , and the AAM in other ethnic minority groups was the same or later com-pared with the local Han girls .

Objective: To analyze the prevalence of reduced visual acuity (VA) and to examine the association between reduced visual acuity and influencing factors among Chinese Han students, so as to provide bases for the prevention and treatment of reduced visual acuity.Methods: Subjects were from 2014 Chinese National Surveys on Students' Constitution and Health (CNSSCH).In this survey, 261 832 Han students aged 7-22 years participated.Unaided distance VA was measured using a retro-illuminated lgMAR chart with tumbling-E optotypes.Ametropia was determined by using serial bronchoscopy.Logistic regression was used to assess the association between reduced visual acuity and influencing factors.ArcMap 10 was used to map the regional distribution of reduced visual acuity.Results: Nationwide, the overall prevalence of reduced visual acuity was 66.6%, and was highest among the urban girls (73.5%).The prevalence of myopia was 60.8% and accounted for more than 90% among the students with reduced visual acuity.Compared with 2010 CNSSCH, the increments of reduced visual acuity were highest in the students aged 13-15 years (6.8 percentage points).The prevalence of reduced visual acuity ranged from 50.6% to 76.2% in each province (autonomous region, municipality) in 2014 CNSSCH.The top three of the prevalence of reduced visual acuity were Jiangsu (76.2%), Zhejiang (76.0%) and Shandong (75.9%), and the lowest three were Hainan (50.6%), Guizhou (53.9%) and Xinjiang (57.6%).Logistic regression showed that the girls, urban students, and students who spent ≥2 h per day in their after school homework were more likely to develop reduced visual acuity, but the students with physical activity time ≥2 h per day were less likely to develop reduced visual acuity.Conclusion: Although the situation was different in each province (autonomous region, municipality), reduced visual acuity has become a public concern affecting the health of students in China.Based on the intervention on the key populations, such as urban girls and pre adolescent students, we should also continue to strengthen the prevention and control for reduced visual acuity among all students.

@@

Objective:To analyze the prevalence of anemia and its proportions of severity,and to exa-mine the association between anemia and nutritional status among Chinese students of ethnic minorities, so as to provide bases for the prevention and treatment of anemia.Methods:The subjects were Mongoli-an,Hui,Zhuang and Korean students aged 7,9,1 2,1 4 and 1 7 years,sampled from the 201 0 Chinese National Surveys on Students’Constitution and Health.World Health Organization (WHO)criteria for screening anemia (2001 )was used,and the proportion rates of mild,moderate and severe were ana-lyzed.The nutritional status was defined according to the growth references of body mass index (BMI)-for-age z-score for 5 -1 9 years developed by the WHO.Stepwise Logistic regression was used to assess the association between anemia and nutritional status,gender,urban /rural areas,age and ethnic minori-ties.Results:The prevalences of anemia were 4.4%,26.4%,6.6% and 5.8% in Mongolian,Hui, Zhuang and Korean students,respectively,of whom,the prevalence of anemia was highest in rural girls and reached 4.8%,42.0%,9.0% and 6.7%,respectively.Most of the ethnic minorities’students belonged to mild anemia,and the prevalence of severe anemia was 1 .4%,1 2.9%,1 .6% and 1 .9% in Mongolian,Hui,Zhuang and Korean students,respectively.Stepwise Logistic regression showed that the girls,rural students,students aged 1 2 years and 1 7 years,Hui,Zhuang and Korean students were more likely to develop anemia than the boys,urban students,students aged 7 years and Mongolian students. The overweight students were less likely to develop anemia compared with the normal students and there was no significant association between anemia and thinness or obesity when the other factors were con-trolled (P >0.05).Conclusion:The epidemic of anemia was different in the different ethnic minorities and the prevalence of anemia in Hui students was of moderate public health concern according to the WHO’s criteria.We should pay more attention to the prevention and treatment of anemia for Hui and eth-nic minorities in rural areas,especially for rural girls.The nutritional status of students could not be a ba-sis or judgement for anemia as there was no significant association between anemia and nutritional status.

Objective:To analyze the secular trends of height among Chinese students aged 17 in dif-ferent ethnic minorities from 1985 to 2010. Methods:A total of 18 Chinese ethnic minorities’ students, including Mongolian, Hui, Uygur, Zhuang, Korean, Tibetan, Miao, Buyi, Dong, Bai, Tujia, Hani, Dai, Lisu, Wa, Nakhi, Tu and Qiang as subjects were sampled from the 1985, 1995, 2000, 2005 and 2010 Chinese National Surveys on Students’ Constitution and Health. The heights of 17 years old people by gender in various ethnic minorities were analyzed and compared. Results:From 1985 to 2010, the in-crements of adult heights increased significantly in many ethnic minorities’ boys. In 2010, the average height of boys aged 17 years in each minority group was higher than 162 cm and was higher than 170 cm among boys from Hui, Mongolian and Korean groups. The ethnics with height growth rates of more than 2 cm per decade in boys were Hui (2. 64 cm/decade) and Dong (2. 05 cm/decade) and the ethnics with height growth rates of more than 1 cm per decade were Korean (1. 99 cm/decade), Tibetan (1. 90 cm/decade), Hani (1. 80 cm/decade) and the other 9 minority groups. The average height of girls aged 17 years in each minority group was higher than 150 cm in 2010 . The heights showed an upward trend in 15 minority groups, but with different degrees. The ethnics with height growth rates of more than 1 cm per decade were Hui (1. 56 cm/decade) and Korean (1. 29 cm/decade). The increments that were signifi-cant between 1985 and 2010 were Hui (3. 89 cm), Korean (3. 23 cm), Dong (2. 35cm) and the other 6 minority groups ( P<0 . 05 ) . Conclusion: Our data suggest that the increments of adult heights may reflect the secular growth change in the major minority groups during the past 25 years, but there was an obvious disequilibrium among various ethnic minorities. We should pay more attention to the minority groups with poor growth and give them more help. Meanwhile, we should also pay attention to the nega-tive effects of the secular growth trend on those minority groups with fast increasing adult height.

Objective: To investigate the association between the combined effect of spermarche/menarche and obesity with elevated blood pressure among Chinese students. Methods: A total of 106 009 primary and secondary school students (55 614 boys and 50 395 girls) were selected from " 2014 National Physical Fitness and Health Surveillance" (including 31 provinces, with the exception of Hong Kong, Macao, and Taiwan) with full record of height, weight, blood pressure, puberty development data of spermarche/menarche. The level of blood pressure, as well as the prevalence of high blood pressure(HBP), were compared between different subgroups (pre-spermarche/menarche and non-obesity group, pre-spermarche/menarche and obesity group, pro-spermarche/menarche and non-obesity group, pro-spermarche/menarche and obesity group), and mulilevel logistic model was used to investigate the relationship between puberty development, obesity and blood pressure. Results: Among 55 614 boys aged 11 to 17 years old, the prevalence of spermarche was 62.1% (34 512/55 614), the prevalence of obesity was 7.5% (4 166/55 614), and the mean values of systolic pressure and diastolic pressure were 110.7/68.2 mmHg (1 mmHg=0.133 kPa). While among 50 395 girls aged 9-14 years, the prevalence of menarche was 48.2% (24 301/50 395), the prevalence of obesity was 5.8% (2 942/50 395), and the mean values of systolic pressure and diastolic pressure was 102.9/64.8 mmHg. The prevalence of high blood pressure was 5.2% (1 003/19 274), 17.9% (328/1 828), 6.6% (2 132/32 174), and 23.9% (558/2 338) in pre-spermarche and non-obesity boys, pre-spermarche and obesity boys, pro-spermarche and non-obesity boys and pro-spermarche and obesity boys, respectively. The prevalence of high blood pressure was 5.9% (1 439/24 570), 17.2% (262/1 524), 5.0% (1 147/22 883), and 17.0% (241/1 418) in pre-menarche and non-obesity girls, pre-menarche and obesity girls, pro-menarche and non-obesity girls and pro-menarche and obesity girls, respectively. After adjustment of region, age, height and urban/rural area by multilevel model, the students in pro-spermarche/menarche and obesity group were more likely to have high blood pressure (boys: OR(95% CI)=4.93 (4.30-5.66); girls: OR(95% CI) =3.77(3.16-4.50)) Conclusion Puberty development and obesity were closed associated with blood pressure. Both boys and girls who enter puberty earlier and were in obesity status were more likely to have high blood pressure. Therefore, interventions focused on obesity prevetion and intervention among prepuberty students may be beneficial to reduce their prevalence of high blood pressure in the future.

Objective: To analyze the urban-rural disparity of childhood stunting and its association with subnational economic growth among Chinese Han students aged 7-18 years. Methods: We used the data from 2014 Chinese National Survey on Students′ Constitution and Health. 213 940 Chinese Han students aged 7-18 years with complete height records were included in this study. Stunting was defined according to the Screening Criteria of Malnutrition for School-age Children and Adolescents(2014 version, in Chinese). We divided students into two groups (economically developed and underdeveloped areas) according to the provincial GDP per capita. Spearman correlation coefficient was used to explore the association between the difference of urban-rural stunting prevalence and the provincial GDP per capita. Logistic regression models were established to assess the risk of stunting in rural children compared with urban children. Results: Among 213 940 students, 107 033 (50.0%) were from urban areas. The average height of 7-18 years old and 18 years old [(152.9±15.7) and (166.1±8.7) cm] of urban students were both higher than those of rural students [(150.7±16.0) and (165.1±8.6) cm] (P<0.001). The stunting prevalence of Chinese urban students (0.4%) was statistically significant lower than that of rural students (1.1%) (P<0.001), which was consistent in all age groups (P<0.05). The urban-rural disparity was found in 60% (18/30) of Chinese provinces. The difference of urban-rural stunting prevalence was negatively associated with provincial GDP per capita (r=-0.62, P<0.001). In economically underdeveloped areas, the risk of stunting for rural students aged 7-9 years was 4.69 (95%CI: 2.93-7.52) times that for urban children, while for students aged 10-18 years, the odds ratio was 2.44 (95%CI: 2.02-2.96). In economically developed areas, the risk of stunting for rural students aged 7-9 years was 5.43 (95%CI: 3.67-8.03) times that for urban children, while for students aged 10-18 years, the odds ratio was 2.15 (95%CI: 1.85-2.49). Conclusions The urban-rural disparity of childhood stunting existed in most places in China. The difference of growth retardation between urban and rural areas was related to regional economic development.

Objective: To compare the prevalence of growth retardation in students aged 7-18 years from 26 minority ethnic groups in China and provides reference evidence to promote the growth and improve the health status of students in minority ethnic groups. Methods: The body height data of students aged 7-18 years in 26 minority ethnic groups in 2014 Chinese National Surveys on Students’ Constitution and Health were used for the analysis and comparison. Growth retardation was defined according to the school-aged child and adolescent malnutrition screening standard (WS/T 456-2014). Results: In 2014, the average body heights of school boys and school girls aged 18 years in 26 ethnic minority groups were (168.3±6.8) cm and (156.2±5.9) cm respectively. The overall growth retardation prevalence rate of school boys and school girls in 26 ethnic groups were 5.4% and 5.1%, respectively. The growth retardation prevalence rate was highest in students of Shui ethnic group (24.5% for boys and 23.0% for girls), and lowest in students of Hui ethnic group (0.1% for boys and 0.3% for girls). The growth retardation prevalence rates in 9 ethnic minority groups were higher than the average level, in these 9 ethnic groups, the differences in prevalence rates of boys of Buyi ethnic group, girls of Lisu ethnic group and girls of Hani ethnic group had no significance among four age groups. Growth retardation in students of Sala ethnic group was mainly observed in age group 7-9 years, but in others ethnic group, for example, Wa ethnic, it was mainly observed in older age group. The students in minority ethnic groups in southwestern China had the highest growth retardation prevalence rate (8.1%), significantly higher than that in northern China (0.8%) (OR=10.6, 95%CI: 7.8-14.4). The overall growth retardation prevalence rate between 7 and 17 years old was negatively correlated with the body height of 18 years old (boys: r=-0.811, P<0.001; girls: r=-0.715, P<0.001). Conclusions In 2014, the differences in body height among students aged 18 years in 26 minority ethnic groups in China were significant. In general, the first five minority ethnic groups with high detection rate of growth retardation in boys were Shui, Wa, Buyi, Yao and Yi, and the five minority ethnic groups with high detection rate of growth retardation in girls were Shui, Yao, Buyi, Wa and Miao. The detection rate of growth retardation was highest in students of minority ethnic groups in southwestern China. Nutritional interventions and healthy education should be carried out in minority ethnic groups and areas with high growth retardation prevalence rate to promote the growth of the students.

Objective: To describe the current situation of spermarche/menarche of 13 ethnic minority groups in China in 2014, and analyze the association between spermarche/menarche and nutritional status among ethnic minority groups. Methods: The sample of 13 ethnic minorities (Bai, Hani, Dai, Lisu, Wa, Naxi, Miao, Shui, Buyi, Dong, Zhuang, Yao and Qiang) from Yunnan, Guizhou, Sichuan province and Guangxi Zhuang autonomous region were selected from Chinese National Survey on Students′ Constitution and Healthy of 2014. A total of 25 964 students with completed records of height, weight, spermarche and menarche were selected, including 11 276 boys aged 11-18 years old and 14 688 girls aged 9-18 years old. Probit analysis was used to calculate the median age at spermarche or menarche. All subjects were classification into four nutritional status groups (normal, malnutrition, overweight and obesity) according to the Screening standard for malnutrition of school-age children and adolescents (WS/T 456-2014) and the Screening for overweight and obesity among school-age children and adolescent (WS/T 586-2018) of China. Binary logistic regression was used to analyze the association between spermarche, menarche and nutritional status. Results: The median age at spermarche (95%CI) of 13 ethnic minorities were ranged from 13.4 (13.1, 13.7) years old to 15.3 (15.1, 15.5) years old. In the 11 -year age group, all ethnic girls experienced menarche. The median age at menarche (95%CI) of 13 ethnic minorities were ranged from 12.1 (11.4, 12.7) years old to13.6 (13.4, 13.7) years old. Logistics regression analysis showed that students with malnutrition experienced spermarche or menarche later than normal weight students, the OR (95%CI) for boys about 0.49 (0.42, 0.56) and girls about 0.15 (0.12, 0.19), while overweight and obese students entered puberty at earlier age, the OR (95%CI) for boys about 1.37(1.10, 1.72) and girls about 3.21(2.51, 4.12). Conclusion Boys from 13 ethnic minorities began to have spermatorrhea at the age of 13, and girls from 13 ethnic minorities began menstruating at the age of 9 in 2014. Nutrition status was closely related to spermarche and menarche.