Abstract The health of children and adolescents is not only related to the growth and wellbeing of individuals, but also to the construction and development of countries. This study reviewed policies that were issued by the central government since the founding of New China which focused on the prevention and treatment of common diseases among school-age children and adolescents. The results revealed that, since the founding of New China, policies for the prevention and control of common diseases among school-age children and adolescents increased in number, and they began to focus on specific rather than general health problems. A gradual emphasis was placed on the specific implementation of prevention and control measures, rather than on guiding principles. Increasingly more attention has been paid to the prevention and treatment of common diseases among school-age children and adolescents.

Objective: To analyze the association between the occurrence of menarche and the exposure to artificial light at night (ALAN) in female Han nationality girls aged 9-18 in China, so as to provide a reference for the research on the disturbance mechanism of ALAN on puberty, as well as provide a scientific evidence for controlling ALAN and making public sanitary policy. Methods: A total of 74 483 Han girls aged 9-18 with complete records of menarche, height, and weight were included in the 2014 Chinese National Surveys on Students Constitution and Health. Pearson correlation was used to explore the correlation between the incidence of menarche and the exposure to artificial light at night in 11-year-old Han girls, and the third quantiles of the area covered by outdoor night lights (0.16, 0.60) and the third quantiles of the average night light intensity [0.97, 5.91 nw/(sr ·cm) 2] were used respectively to divide the study subjects into 3 groups, and the multifactor Logistic regression model was used to analyze the effect of artificial light at night exposure on menarche. Results: In 2014, the median age of menarche of Chinese Han girls was 12.18 years old, and the incidence of menarche in the 11-year-old group was 26.31%. After controlling for body mass index, local population and the logarithmic values of per capita GDP, the incidence of menarche of 11-year-old Han girls was positively correlated with the local outdoor average night light coverage area ratio and the night average light intensity logarithmic adjustment value( r =0.29, 0.30, P <0.05).The higher the local outdoor night light coverage area ratio ( OR =1.28, 1.52) and the average night light intensity ( OR =1.47, 1.58), the higher the incidence of menarche in 11-year-old Han girls( P <0.05). Conclusion There is a positive correlation between artificial light at night exposure and the menarche rate of 11-year-old Han girls. Research on artificial light at night exposure may provide scientific evidence on puberty onset and its effects on population health.

Objective: To construct core information about physical activities of Chinese students aged 7-18 years, so as to provide a reference for impoving the level of adolescents physical activities. Methods: Canadian 24 Hour Movement Guidelines for Children and Youth was used as a framework, the preliminary core recommendations on physical activity for Chinese students aged 7-18 years were developed based on qualitative research. Recommendations covered three scales, including physical activity, sedentary behaviour and sleep. Physical activity included four subscales of frequency, intensity, duration and type, while sedentary behaviour and sleep only included one subscale. Three rounds of consultation were conducted using Delphi method. In the second round of consultation, the results of 2014 Chinese National Surveys on Students Constitution and Health were presented to experts for reference. In the third round of consultation, experts need to rank the importance of seven items of physical fitness under the physical activity type subscale by age group through analytic hierarchy process. Results: Totally 25, 25, and 18 experts were consulted in three rounds respectively. The questionnaire response rates in 3 rounds were 100.0%, 100.0%, and 94.4%, respectively. The authority coefficients were 0.92, 0.93, and 0.91. The harmony coefficients were 0.63( χ 2=237.10, P <0.01), 0.63( χ 2= 242.60 , P <0.01), and 0.76( χ 2=97.05, P <0.01). It was recommended that students aged 7 to 18 years in China should do moderate to vigorous physical activity for a cumulative total of at least 60 minutes per day, and most of the 60 minutes or more per day should be either moderate or vigorous intensity aerobic physical activity. Of the daily physical activity, students should conduct vigorous intensity aerobic physical activity, muscle strengthening and bone strengthening physical activity on at least 3 days a week. At least 2 hours of daytime outdoor activity was recommended for primary school students and 1 hour for secondary school students. 7-12 year old students should do more physical activities that enhance flexibility, coordination and agility, while 13-18 year old students should do more physical activities that enhance strength, endurance and speed. Sedentary behaviour included one subscale, where students should reduce sedentary behaviour, break up long periods of sitting as often as possible, and limit recreational screen time and online study time. Sleep included one subscale of duration.Students should get sufficient and uninterrupted sleep per night. Conclusion The development of core recommendations on physical activity for Chinese students aged 7 to 18 might help improve physical activity levels and promote health of children and adolescents.

Objective: To analyze the hotspots, frontiers, and future research trends related to puberty development among children and adolescents from 2013 to 2022, and to provide a reference for subsequent research related to puberty development. Methods: Data related to puberty development from 2013 to 2022 were retrieved from the Web of Science core collection with the search formula "puberty timing (title) OR puberty development (title) OR pubertal timing (title) OR pubertal development (title) OR puberty timing (abstract) OR puberty development (abstract) OR pubertal timing (abstract) OR pubertal development (abstract)". The CiteSpace was used for visual analysis. Results: A total of 6 684 publications were obtained and an upward trend could be seen in the number of publications in the field of puberty development in the last 10 years. Researchers with a high number of publications were Juul Anders, Brix Nis, and Ernst Andreas, in addition, the United States had the highest number of publications ( 2 125 ) and the highest betweenness centrality (0.23) in this field. In the last decade, research hotspots had focused on the timing of pubertal initiation, biological mechanisms of pubertal development, and sex differences in pubertal development. Research on environmental endocrine disruptors and the mechanisms of pubertal development were at the forefront of research and future research trends. Conclusion Scholars can refer to the research hotspots and research trends in this field and focus on the issues related to environmental endocrine disruptors and pubertal development mechanisms.

Objective: To analyze physical fitness and health status and gender differences of middle school students among 5 minorities (Mongolian, Hui, Uyghur, Zhuang and Korean), and to provide the theoretical basis for the strategy formulation. Methods: The present data came from 3 waves of Chinese National Survey on Students Constitution and Health (2010, 2014, and 2019). According to National Standards for Students Physical Health (2014 Revision), excellent, and excellent good physical fitness and health status were defined. Cochran Armitage test was used to examine the trends of physical fitness and health status. Chi square test and Logistic regression were used to analyze the difference of physical fitness and health status by sex and survey year. Results: From 2010 to 2019, the excellent physical fitness and health status rate of Mongolian, Hui, Uyghur, Zhuang and Korean students increased from 1.8%, 0.7%, 0.3%, 0.5% and 1.3% to 4.3%, 2.8%, 1.2%, 1.3% and 3.5%, respectively. The excellent good physical fitness and health status rate of Mongolian, Hui, Uyghur and Zhuang students increased from 12.9%, 8.0%, 7.2 % and 8.4% to 24.7%, 20.1%, 12.6% and 19.8%( Z =6.15，6.71，4.12，3.06，5.26；11.88，13.42，6.70，11.08， P <0.05), respectively. In 2019, students aged 13 to 15 years showed higher proportion of excellent/excellent good physical fitness and health status than that of students aged 16 to 18. Boys were more likely to be in excellent/excellent good physical fitness and health status than girls from 2010 to 2019. The sex difference in excellent/excellent good physical fitness and health status narrowed during 2010 and 2019. Conclusion Physical fitness and health status of minority students improved while sex difference narrowed during last decade, but there is still a long way to reach the goal proposed by China. Targeted intervention should be proposed to promote physical fitness and health status in accordance with the developmental characteristics, especially for girls and students aged 16 to 18 years.

Objective:We aimed to assess the effects of outdoor time in preventing incident myopia among primary school students and evaluate its differences among different grades to provide evidence for policy formulation related to myopia prevention.Methods:This study is a cohort study. We investigated 6 046 grade 1 to 5 students in 9 provinces, Jiangsu, Shanghai, Fujian, Shanxi, Henan, Hunan, Gansu, Chongqing, and Guangxi. In 2019, we measured their myopia on site. In 2020, we did a follow-up visit on those students to detect the myopia incidence rate. Information regarding outdoor time and myopia-related behaviors were obtained from a questionnaire within one week of visual acuity measurement in 2020. The chi-square test and Cochran-Armitage trend test compared the differences between groups. The Cox proportional hazards risk model was used to test the relationship between outdoor time and myopia.Results:In 2020, the overall myopia incidence rate of grade 1 to 5 students in the baseline was 27.5%; while 23.0% in grades 1 and 2 students and 31.7% in grades 3 to 5 students, respectively. After controlling for covariates, for students in grade 1 to 2, those with ≥1 hour of outdoor time per day were at 0.76 (95% CI: 0.62-0.93, P=0.008) times risk of being myopia than that of students with <1 hour of outdoor time per day; while for students in grades 3 to 5, an average of ≥3 hours of outdoor time per day was required to have a significant protective effect on myopia. The students with ≥3 hours of outdoor time per day were less likely to be myopia ( OR=0.75, 95% CI: 0.61-0.93, P=0.007) than those students with <3 hours of outdoor time per day. Conclusions:For grade 1 and 2 students, 1 hour of outdoor time per day could reduce the incidence of myopia, whereas for grade 3 to 5 students, 3 hours of outdoor time per day could effectively reduce the incidence of myopia. Therefore, the recommendations for outdoor time as myopia prevention should be different for different grades. The higher the grade is, the more outdoor time should be spent to reduce myopia incidence. Moreover, other factors that affect myopia's incidence should be also paid attention to, and a comprehensive approach should be adopted to prevent and control the incidence of myopia.

Objective:To describe the prevalence of psychological distress and to analyze its influencing factors among Chinese children and adolescents aged 9-18 years in 2019.Methods:Data was from the 2019 Chinese National Survey on Students' Constitution and Health, and 148 892 children and adolescents were included. Psychological distress was measured using the Kessler Psychological Distress Scale (K10): scores ≤19 were defined as no psychological distress, scores between 20-24 were defined as mild psychological distress, scores between 25-29 were defined as moderate psychological distress, and scores ≥30 were defined as severe psychological distress (moderate to severe psychological distress were defined as high psychological distress). The ANOVA, t test, and χ2 test were used to compare the differences in K10 scores and high psychological distress rates among children and adolescents with different characteristics. The ANOVA and trend χ2 test were used to analyze the trends. Modified-Poisson regression models were used to determine influencing factors of high psychological distress. Results:The K10 scores for Chinese children and adolescents aged 9-18 years in 2019 was 21.5±9.2, and their rate of high psychological distress was 31.6%. The rates of high psychological distress among children and adolescents aged 9-12, 13-15, and 16-18 years were 22.3%, 35.9%, and 38.8%. K10 scores and rates of high psychological distress showed an increasing trend as age increased (trends test all P<0.001). K10 scores and rates of high psychological distress were higher among children and adolescents who were older, female, rural, in areas with medium to low GDP per capita level, and with lower parental education (all P<0.001). Multifactorial modified-Poisson regression analysis showed that children and adolescents aged 13-15 years, 16-18 years, female, rural, and in areas with low to moderate GDP per capita level were at higher risk of high psychological distress (all P<0.05), with a OR (95% CI) of 1.55 (1.52-1.58), 1.66 (1.63-1.69), 1.07 (1.05-1.09), 1.02 (1.01-1.04), 1.10 (1.07-1.12). Children and adolescents in areas with medium to high GDP per capita level, whose father had a secondary or high school degree, whose father had a college degree or above, whose mother had a secondary or high school degree, and whose mother had a college degree or above were at lower risk of high psychological distress (all P<0.05), with a OR (95% CI) of 0.96 (0.94-0.98), 0.92 (0.90-0.93), 0.84 (0.82-0.86), 0.95 (0.93-0.97), 0.86 (0.83-0.88). Conclusions:The prevalence of psychological distress was high among Chinese children and adolescents aged 9-18 years in 2019, which is a vital problem. Mental health interventions need to be implemented among children and adolescents that were older, girls, rural, live in areas with lower economic levels, and whose parents have a lower education level.

Objective:To analyze the association between the occurrence of spermarche and menarche and psychological distress among Chinese Han children and adolescents aged 9 to 18 years.Methods:Data were drawn from the 2019 Chinese National Survey on Students' Constitution and Health, and a total of 54 438 boys aged 11 to 18 years and 76 376 girls aged 9 to 18 years with psychological distress, spermarche/menarche records were included in the final analysis. The occurrence of spermarche/menarche was recorded by physicians, and psychological distress was classified according to the Kessler Psychological Distress Scale scores. The chi-square test was used to compare the difference between groups in the occurrence of spermarche/menarche, and the multinomial logistic regression model and stratification analysis was established to analyze the association between psychological distress and spermarche/menarche.Results:The incidence of spermarche/menarche in 2019 ranged from 6.3% to 96.5% for eight age groups of Chinese boys and 2.8% to 99.0% for ten age groups of girls. The rates of high psychological distress among boys and girls were 32.5% and 32.7%. Among boys aged 11 to 18 years, the rate of high psychological distress increased with age, with a trend test P<0.001, and the difference in the rate of high psychological distress between those who had and had not had their spermarche was not statistically significant in all age groups. Among girls aged 9 to 18 years, the rate of high psychological distress increased with age, with a trend P<0.001; the rate of high psychological distress was higher in the group with menarche at age 10 and 12 than in the group without menarche (all P<0.05). High psychological distress was positively correlated with spermarche among boys aged 13-15 years living in urban areas and hight level economic development areas ( OR=1.11, 95% CI: 1.02-1.21; OR=1.18, 95% CI: 1.06-1.32). Overall, high psychological distress was positively correlated with menarche in girls aged 9-12 and 13-15 years ( OR=1.33, 95% CI: 1.25-1.42; OR=1.22, 95% CI: 1.07-1.39). High psychological distress was positively correlated with menarche among girls aged 9-12 years living in different regions except for the Northeast region, in areas with different levels of economic development, and in urban and rural areas, in girls aged 13-15 years living in urban, central, and western regions, and in girls aged 16-18 years residing in the central region. Conclusions:This study found an association between the occurrence of spermarche/menarche and psychological distress among Chinese Han children and adolescents aged 9 to 18 years in 2019, which was particularly significant among girls aged 9 to 12 years and boys aged 13 to 15 years living in areas with higher levels of socioeconomic development.

Objective:To describe the status of physical fitness of children and adolescents aged 13-18 years in China in 2019 and analyze its association with psychological distress.Methods:Data were drawn from the 2019 Chinese National Survey on Students' Constitution and Health, and 90 633 Han children and adolescents aged 13-18 years were included. Physical fitness was evaluated by "National Students Constitutional Health Standards" (2014 revised edition). Psychological distress was classified according to the scores of the Kessler Psychological Distress Scale: ≤19, 20-24, 25-29, and ≥30 scores indicated no, mild, moderate, and severe psychological distress, respectively, with moderate and severe psychological distress collectively referred to as high psychological distress. The χ2 test was used to compare the distribution differences between boys and girls, the Cochran-Armitage test was used to analyze the trend, and the multinomial logistic regression in the mixed effect model was established to analyze the association between physical fitness and psychological distress. Results:In 2019, the unqualified rate of physical fitness among children and adolescents aged 13-18 years in China was 17.2%, and the prevalence of excellent and good physical fitness was 18.2%, which was lower among boys (15.9%) than girls (20.5%) with a statistically significant difference ( P<0.05). The excellent and good physical fitness rate showed a significantly decreasing trend with age (trend test P<0.05). The rate of high psychological distress among children and adolescents aged 13-18 years in China in 2019 was 39.3%, with boys (37.0%) having a lower prevalence than girls (41.6%), supported by a statistically significant difference ( P<0.05), and a decreasing trend with the degree of physical fitness was observed both in boys and girls (trend test P<0.05). The multinomial logistic regression model showed that the prevalence of moderate ( OR=0.83, 95% CI: 0.79-0.88, P<0.001) and severe ( OR=0.81, 95% CI: 0.77-0.86, P<0.001) psychological distress were both lower in children and adolescents with excellent and good physical fitness. Conclusion:The status of physical fitness and psychological distress of Chinese children and adolescents aged 13-18 in 2019 was not optimistic, with physical fitness showing a significantly negative association with psychological distress.

BACKGROUND: Non-transport unintentional injuries (NTUIs) are major public concerns, especially among children and adolescents in low- and middle-income countries. With environmental and cognitive changes, a recent systematic description of global trends and regional differences concerning NTUIs is urgently needed for the global agenda of relevant policy-making and intervention target findings. METHODS: We used mortality, population, and socio-demographic-index (SDI) data from Global Burden of Disease 2019 to analyze the trends of NTUIs mortality. We applied the slope index of inequality (SII) and relative index of inequality (RII) to measure the absolute and relative inequality between countries and territories. The concentration curve and concentration index (CI) were also used to measure the inequality. We conducted a sensitivity analysis to make our findings credible. RESULTS: In 2019, there were 205,000 deaths due to NTUIs among children and adolescents aged 5 to 24 years, which decreased from 375,000 in 1990. In 2019, the age-standardized mortality rate (ASMR) was 8.13 per 100,000, ranging from the lowest in the Netherlands (0.90 per 100,000) to the highest in the Solomon Islands (29.34 per 100,000). The low-middle SDI group had the highest ASMR of NTUIs, while the low SDI group had the slowest decrease. After excluding the death caused by "exposure to forces of nature" and "other unintentional injuries", drowning accounted for the most deaths in almost every SDI group, gender, and age group, but the major causes of death varied in different subgroups. For example, animal contact was a major cause in low and low-middle SDI groups but less in high SDI groups, while high and high-middle SDI groups had a higher proportion of deaths for foreign body and poisonings. The SII showed a declining trend, but the RII and CI did not, which might indicate that inequality was persistent. Similar results were found in the sensitivity analysis. CONCLUSIONS Despite the declining trend of the mortality rate and the narrowing gap between countries, there were still a large number of children and adolescents dying from NTUIs, and those experiencing social-economic disadvantages remained at high mortality. Embedding the prevention of NTUIs into sustainable development goals might contribute to the progress of reducing death and inequalities, which ensures that no one is left behind.
Global Burden of Disease