Long-term trends and urban-rural disparities in the physical growth of children and adolescents in China: an analysis of five national school surveys over three decades

Height development trends among 7-18-year-old school-age children in central plains of China between 2000 and 2019: A serial cross-sectional surveillance study in China

OBJECTIVE

The aim of this study was to analyze changes in height of 7-18-year-old school-age children in China during the year of 2000-2019.

METHODS

We used the survey data from the Chinese National Survey on Students' Constitution and Health in Henan Province for the years 2000, 2005, 2010, 2014, and 2019. Data were categorized into subgroups based on geographic location, gender, and age; mean, standard deviation, and Pearson's correlation coefficient were used to analyze trends in height change among children and adolescents and the correlation between socioeconomic indicators and height change.

RESULTS

The height of children and adolescents in Henan has shown a continuous upward trend. The height difference between urban and rural areas has gradually narrowed but has not disappeared. The correlation of height development trends between neighbouring urban areas was higher than in other areas. The level of medical care was significantly associated with the change in height for both boys (r = 0.950, p = 0.013) and girls (r = 0.897, p = 0.039); GDP per capita (r = 0.940，p = 0.018) was significantly associated with the change in height for boys only.

CONCLUSION

The height of Chinese children and adolescents will continue to maintain a positive growth trend, but we need to pay attention to the health status and nutritional intake of children and adolescents in economically disadvantaged areas in order to narrow the height disparity between different socio-economic groups.

The impact of long-term exposure to NO2, O3, and their oxidative potential on adolescents' mental health, and the protective role of school-based greenness

Recent increases in nitrogen dioxide (NO2) and ozone (O3), two highly reactive and oxidative pollutants, have raised concerns about their potential impact on adolescent mental health. This study leveraged data from the Chinese National Survey on Students' Constitution and Health (CNSSCH) in 2019, a nationally representative cross-sectional survey of Chinese adolescents. A total of 149,697 adolescents aged 10-18 years were included in this study. NO2 and O3 were sourced from the ChinaHighAirPollutants dataset, and the combined oxidative potential (OX) was subsequently calculated using the concentrations of NO2 and O3. The study quantitively examined the association of NO2, O3, and OX with adolescent mental health using the Dual Factor Model of Mental Health (DFM), which was derived from a questionnaire. According to the DFM, mental health status was divided into four groups: complete mental health, vulnerable, symptomatic but content, and troubled. Greenness around schools, measured by the Normalized Difference Vegetation Index (NDVI), was examined for its potential effect modification on the association between NO2, O3, OX, and mental health. Each IQR (Interquartile Range) increase in OX was related to adverse mental health outcomes, with ORs of 1.17 (95 % CI: 1.06, 1.29) for being vulnerable, 1.20 (95 % CI: 1.12, 1.28) for being more symptomatic but content, and 1.15 (95 % CI: 1.07, 1.23) for being troubled. Similar findings emerged in relation to O3 exposure. A positive association was observed between NO2 exposure and being vulnerable (OR = 1.07; 95 % CI: 1.01, 1.16). Additionally, the impact of exposure to NO2, O3, and OX on mental health outcomes was significantly stronger in the low-level NDVI group compared to the high-level NDVI group (P for interaction < 0.05). The joint effects analysis revealed that adolescents exposed to high levels of air pollutants and low NDVI had the highest odds of adverse mental health outcomes. These results highlight the complex relationship between NO2, O3, OX, and mental health, with particular emphasis on the underexplored role of OX. Notably, the findings suggest that reducing pollution and increasing greenery could offer significant benefits for improving adolescent mental health.

Control of childhood obesity and implications for policy in China

Prevention and control of childhood obesity in China is complex. Despite numerous existing policy endeavours, particularly Healthy China 2030, accompanied by multiministerial initiatives, childhood obesity persists and even exacerbates. In this paper, we review current national policies, assess progress of the existing system managing childhood weight, and identify implementation challenges. Leveraging insights from existing literature and guided by a PEDALS (ie, problem, evidence-based practice, determinants, actions, long term, and scalability) framework, we propose a strategy to refine and integrate current policies, interventions, and research into a policy framework, embedding evidence-based practices into practical solutions for childhood obesity prevention and control in China.

Determinants of childhood obesity in China

Over the past four decades, China has witnessed an important nutritional transition, characterised by a heightened overnutrition burden among children. The country now has the largest population of children with obesity globally. In this paper, we review the epidemiology of childhood obesity in China, its determinants, and risk factors, with a particular focus on school-aged children. Evidence unveils substantial variations across age, gender, and region. We describe multilevel obesogenic determinants, including macro-level social, cultural, and environmental factors; meso-level factors related to schools and communities; and micro-level factors tied to families and individuals from the perinatal-infant stage to childhood and adolescence. The primary drivers of childhood obesity appear to be rooted in the broader macro-level social, economic, and technological environment; obesogenic factors, which have affected school, community, and family environments; and accelerated unhealthy behaviour uptake. Identifying and characterising the catalysts behind the rise in childhood obesity in China is imperative for the development of scalable, effective, and tailored prevention, control, and intervention strategies.

Trends and inequalities in thinness and obesity among Chinese children and adolescents: evidence from seven national school surveys between 1985 and 2019

BACKGROUND

There are little recent data in China regarding contemporary nutritional inequities among children and adolescents, particularly in relation to urban-rural residence and regional socioeconomic status (SES). We aim to assess inequalities in thinness and obesity in Chinese children and adolescents.

METHODS

Weight and height measurements for 1 677 261 children and adolescents aged 7-18 years were obtained from seven cycles of the Chinese National Surveys on Students Constitution and Health (1985, 1995, 2000, 2005, 2010, 2014, and 2019). Sex-specific BMI-for-age Z scores were applied to define thinness (Z scores <-2SD) and obesity (Z scores >+2SD). Urban-rural classification came from the Statistical Urban and Rural Division Code, and gross domestic product (GDP) per capita in the province in which the school was situated was used as a proxy for SES. T1 represented the provinces with the most disadvantaged SES and T3 represented the provinces with the most advantaged SES. General linear regression models assessed correlations between prevalence and GDP per capita, with projections to 2030 derived from best-fitting models.

FINDINGS

The mean prevalence of obesity rose from 0·10% (95% CI 0·09 to 0·11) in 1985 to 8·25% (8·13 to 8·37) in 2019, whereas thinness prevalence decreased from 8·49% (8·41 to 8·58) to 3·37% (3·29 to 3·45). High SES provinces exhibited a significant drop in obesity prevalence from 2014 (8·42% [8·19 to 8·65]) to 2019 (7·73% [7·52 to 7·95]). Nationally, the prevalence of obesity was consistently higher in urban areas than in rural areas for both sexes from 1985 to 2019; however, a greater prevalence of obesity was observed in rural than urban girls residing in T3 regions in 2019 (urban-rural gap: -0·37% [-0·07 to -0·80]). Rural boys had a higher prevalence of thinness than their urban counterparts across all survey waves, with the exceptions of 1985 and 1995. For girls, no significant urban-rural gap in thinness was observed in the most recent survey in 2019 (-0·10% [-0·24 to 0·04]). From 1985 to 2014, boys and girls from high SES regions had a higher risk of obesity and a lower risk of thinness than those from low SES regions. However, in 2019, a nationwide shift occurred, and the T3-T1 difference in obesity approached or went below zero for boys (-0·49% [-1·02 to 0·04]) and girls (-0·68% [-1·00 to -0·35]). T3-T1 differences in thinness also approached zero for boys (-0·46% [-0·77 to -0·14]) and girls (-0·14% [-0·43 to 0·15]). The projected estimates to 2030 for urban-rural obesity gaps (boys: -1·00% [-2·65 to 0·65]; girls: -2·88% [-6·91 to 1·15]) and T3-T1 obesity differences (boys: -8·88% [-13·76 to -4·01]; girls: -8·82% [-12·78 to -4·85]) were both negative, with forecasted estimates for urban-rural gaps and T3-T1 differences in thinness prevalence in 2030 close to zero for both boys and girls.

INTERPRETATION

China's socioeconomic development continues to influence within-country inequities regarding the regional distribution of child and adolescent weight according to urban-rural location and regional SES. Contemporary Chinese children and adolescents in socioeconomically disadvantaged regions and rural areas constitute a vulnerable population facing nutritional risk, but from obesity rather than thinness. Disrupting projected inequities in obesity will require extensive preventive investments.

FUNDING

National Natural Science Foundation of China, Beijing Natural Science Foundation, Peking University Talent Introduction Program Project, and Clinical Medicine Plus X-Young Scholars Project of Peking University.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

EQ‑5D‑Y-3L population norms for children and adolescents in Jiangsu, China

OBJECTIVE

This study aims to establish EQ-5D-Y-3L population norms in Jiangsu, China by conducting a large-scale cross-sectional survey.

METHODS

Children and adolescents aged 9-17 from three cities of Jiangsu Province were selected by multistage stratified random sampling to complete the EQ-5D-Y-3L instrument independently. Population norms for Jiangsu, China were determined by calculating statistics based on age and gender. Logistic and Tobit regression models were employed to explain the relationship between HRQoL and factors such as sociodemographic characteristics/recent acute symptoms (experienced fever/cough/sore throat/diarrhea in the past two weeks).

RESULTS

Three cities yielded 37,574 valid samples (a sample validity rate of 95.4%). The EQ-5D-Y-3L utility values (mean ± SD) were 0.964 ± 0.085 for males and 0.958 ± 0.077 for females. Males scored 85.94 ± 19.62 and females scored 84.83 ± 18.45 on the VAS (mean ± SD), while the percentages of respondents reporting full health ranged from 58.3 to 78.8%. The dimension in which most respondents reported having no problems was "feeling worried, sad, or unhappy" (23.0%). And the lowest HRQoL was shown in the 14-year-old age group. Gender, age, board at school, and BMI were found to have an association with HRQoL. In addition, recent acute symptoms also correlate with some aspects of HRQoL.

CONCLUSIONS

This study established EQ-5D-Y-3L population norms in Jiangsu, China for the first time. These norms will support resource allocation decision-making and be used as a reference for health evaluation studies.

Malnutrition in infants aged 6-23 months in China's poorest rural counties from 2016 to 2021: cross sectional study

OBJECTIVES

To assess trends and differences in child malnutrition by population subgroups among infants aged 6-23 months in China's poorest rural counties.

DESIGN

Six consecutive cross sectional surveys were conducted annually.

SETTING

The study was conducted in 116 counties in 19 provinces from 2016 to 2021, representing China's 832 poorest counties.

PARTICIPANTS

A total of 210 088 participants were selected through a multistage cluster sampling procedure; all participants were infants aged 6-23 months.

MAIN OUTCOME MEASURES

Prevalence of anaemia, stunting, wasting, overweight, and growth status in children (measured by length-for-age and weight-for-length z scores).

RESULTS

Four main malnutrition forms were prevalent in 2016: anaemia (prevalence 18.3%), stunting (7.5%), wasting (4.7%), and overweight (3.1%). The prevalence of any two coexisting malnutrition forms was low. All four forms of malnutrition decreased from 2016 to 2021. Anaemia decreased by more than half, with an annual reduction rate of 9.11% (95% confidence interval (CI) 4.83% to 13.20%). Stunting was reduced by over a third, with an annual reduction rate of 10.44% (7.56% to 13.22%), which is faster than the World Health Organization's target of 3.9%. Differences in child growth by county gross domestic product quarters were small and decreased over time, but growth differences related to education persisted. Infants whose mothers completed education up to primary school level had approximately twice the risk of stunting (adjusted rate ratio 2.29 (95% CI 1.87 to 2.81)) and wasting (1.73 (1.40 to 2.13)) compared with children whose mothers had an education level of a college degree or above. Boys had poorer growth and higher anaemia than did girls. For all outcomes, differences related to sex and education were greatest at 6 months of age.

CONCLUSIONS

Education related inequalities in growth of infants persists, with these differences particularly affecting children whose mothers completed education only up to primary school level.

Depression, anxiety, and development of obesity from childhood to young adulthood in China

OBJECTIVE

To examine the cross-sectional and longitudinal bidirectional associations of depression and anxiety symptoms with the development of obesity over time among children and adolescents in different age groups from childhood to young adulthood.

METHODS

This is a three-wave longitudinal study that included >200,000 school-aged children between 5 and 18 years. Participants were assessed at baseline, 6 months, and 12 months. Depression and anxiety symptoms, as well as participants' weight and height, were collected at each assessment. The cross-sectional associations between obesity and depression or anxiety were examined through ANOVA and Chi-square tests. Multivariable logistic regression analyses were performed to investigate their longitudinal bidirectional associations.

RESULTS

The prevalence of obesity reached a peak in the age group between 12 and 14 years. Concurrently, higher mean BMI and obesity prevalence were associated with more severe symptoms of depression and anxiety in each age group (ps < 0.001). Longitudinally, depression and anxiety significantly increased the risk of development of obesity over time (odds ratios [ORs] = 1.08 to 1.77). Moreover, obesity significantly aggravated the risk of development of depression (ORs = 1.17 to 1.68) and anxiety (ORs = 1.25 to 1.71) over time and hindered the alleviation of depressive (ORs = 0.68 to 0.79) and anxiety symptoms (ORs = 0.73 to 0.74).

CONCLUSION

Findings suggest that there were bidirectional associations between obesity and psychological distress. It may be important to continuously track BMI and psychological conditions for children and adolescents over time to avoid the reinforcement of their negative reciprocal interactions.

Intergenerational care and rural childhood obesity in the digital era: Based on screen exposure perspective

Background

Rural Chinese children are experiencing increasing obesity rates, yet studies often neglect the impact of IT and screen media growth on obesity risks in the context of intergenerational care, leading to incomplete strategies for the digital era.

Methods

By comprehensively utilizing the data on rural children aged 6-17 from the China Family Panel Studies (CFPS) and the China Health and Nutrition Survey (CHNS), this study aims to test the logical chain and specific mechanisms regarding "intergenerational care - screen exposure - rural childhood obesity". We employ the Propensity Score Matching (PSM) and Generalized Propensity Score Matching (GPSM) methods to respectively address the self-selection biases associated with inter-generational care and children's screen exposure behaviors.

Results

1) Intergenerational care significantly increases screen exposure among rural children. 2) Gender bias increases the risk of screen exposure for rural boys under intergenerational care. 3) Children with higher screen exposure levels are more affected by intergenerational care, which further undermines parental supervision. 4) Children's screen exposure leads to increased sedentary time and higher probability of purchasing unhealthy foods, thereby exacerbating obesity. This process is facilitated by enhancing preferences for snacks, fast food, and beverages, and weakening preferences for physical activity. 5) GPSM analysis indicates that children's screen exposure has an inverted "U"-shaped impact on unhealthy dietary preferences and a "U"-shaped impact on activity preferences. It results in a nonlinear positive impact of screen exposure on obesity. This study reveals a positive association between screen exposure and obesity, offering new insights into how intergenerational care in the digital era may elevate obesity prevalence through excessive screen time for rural children.

Body composition trajectories during childhood predict skeletal maturation at puberty: A longitudinal study

Nutritional status significantly impacts linear bone growth. We aimed to determine the relationship between the trajectories of four body composition indicators and pubertal advanced bone age. Trajectories of body mass index z-score (BMI z-score), visceral fat area z-score (VFA z-score), fat mass index z-score (FMI z-score), and fat-free mass index z-score (FFMI z-score) were identified based on three body composition measurements conducted from October 2018 to April 2023 within a pediatric cohort (the PROC study). We assessed pubertal bone age using the Tanner-Whitehouse 3-Chinese Radius-Ulna-Short (TW3-C RUS) method among 1402 primary school children. Children with a trajectory of higher BMI z-score, VFA z-score, FMI z-score, and FFMI z-score since childhood were more likely to have advanced bone age. The risk of advanced bone age was higher in children who were consistently in the high VFA z-score group (odds ratio [OR] = 6.73) or consistently in the high BMI z-score group (OR = 5.57), as compared to those in the low VFA z-score and low BMI z-score groups. Regular monitoring and maintenance of normal VFA during childhood may reduce the risk of advanced bone age at puberty. Furthermore, BMI monitoring is optional, especially in cases where specialized body composition equipment is not available.

Establish a noninvasive model to screen metabolic dysfunction-associated steatotic liver disease in children aged 6-14 years in China and its applications in high-obesity-risk countries and regions

Background

The prevalence of metabolic-associated steatotic liver disease (MASLD) is rising precipitously among children, particularly in regions or countries burdened with high prevalence of obesity. However, identifying those at high risk remains a significant challenge, as the majority do not exhibit distinct symptoms of MASLD. There is an urgent need for a widely accepted non-invasive predictor to facilitate early disease diagnosis and management of the disease. Our study aims to 1) evaluate and compare existing predictors of MASLD, and 2) develop a practical screening strategy for children, tailored to local prevalence of obesity.

Methods

We utilized a school-based cross-sectional survey in Beijing as the training dataset to establish predictive models for screening MASLD in children. An independent school-based study in Ningbo was used to validate the models. We selected the optimal non-invasive MASLD predictor by comparing logistic regression model, random forest model, decision tree model, and support vector machine model using both the Beijing and Ningbo datasets. This was followed by serial testing using the best performance index we identified and indices from previous studies. Finally, we calculated the potential MASLD screening recommendation categories and corresponding profits based on national and subnational obesity prevalence, and applied those three categories to 200 countries according to their obesity prevalence from 1990 to 2022.

Findings

A total of 1018 children were included (NBeijing = 596, NNingbo = 422). The logistic regression model demonstrated the best performance, identifying the waist-to-height ratio (WHtR, cutoff value ≥0.48) as the optimal noninvasive index for predicting MASLD, with strong performance in both training and validation set. Additionally, the combination of WHtR and lipid accumulation product (LAP) was selected as an optimal serial test to improve the positive predictive value, with a LAP cutoff value of ≥668.22 cm × mg/dL. Based on the obesity prevalence among 30 provinces, three MASLD screening recommendations were proposed: 1) "Population-screening-recommended": For regions with an obesity prevalence ≥12.0%, where MASLD prevalence ranged from 5.0% to 21.5%; 2) "Resources-permitted": For regions with an obesity prevalence between 8.4% and 12.0%, where MASLD prevalence ranged from 2.3% to 4.4%; 3) "Population-screening-not-recommended": For regions with an obesity prevalence <8.4%, where MASLD prevalence is difficult to detect using our tool. Using our proposed cutoff for screening MASLD, the number of countries classified into the "Population-screening-recommended" and "Resources-permitted" categories increased from one and 11 in 1990 to 95 and 28 in 2022, respectively.

Interpretation

WHtR might serve as a practical and accessible index for predicting pediatric MASLD. A WHtR value ≥0.48 could facilitate early identification and management of MASLD in areas with obesity prevalence ≥12.0%. Furthermore, combining WHtR ≥0.48 with LAP ≥668.22 cm × mg/dL is recommended for individual MASLD screening. Moreover, linking these measures with population obesity prevalence not only helps estimate MASLD prevalence but also indicates potential screening profits in regions at varying levels of obesity risk.

Funding

This study was supported by grants from Capital's Funds for Health Improvement and Research (Grant No. 2022-1G-4251), National Natural Science Foundation of China (Grant No. 82273654), Major Science and Technology Projects for Health of Zhejiang Province (Grant No. WKJ-ZJ-2216), Cyrus Tang Foundation for Young Scholar 2022 (2022-B126) and Sino-German Mobility Programme (M-0015).

Matching actions to needs: shifting policy responses to the changing health needs of Chinese children and adolescents

China is home to the second largest population of children and adolescents in the world. Yet demographic shifts mean that the government must manage the challenge of fewer children with the needs of an ageing population, while considering the delicate tension between economic growth and environmental sustainability. We mapped the health problems and risks of contemporary school-aged children and adolescents in China against current national health policies. We involved multidisciplinary experts, including young people, with the aim of identifying actionable strategies and specific recommendations to promote child and adolescent health and wellbeing. Notwithstanding major improvements in their health over the past few decades, contemporary Chinese children and adolescents face distinct social challenges, including high academic pressures and youth unemployment, and new health concerns including obesity, mental health issues, and sexually transmitted infections. Inequality by gender, geography, and ethnicity remains a feature of health risks and outcomes. We identified a mismatch between current health determinants, risks and outcomes, and government policies. To promote the health of children and adolescents in China, we recommend a set of strategies that target government-led initiatives across the health, education, and community sectors, which aim to build supportive and responsive families, safe communities, and engaging and respectful learning environments. TRANSLATION: For the Chinese translation of the abstract see Supplementary Materials section.

Impact of home quarantine on physical fitness of school-aged children in Xi'an during COVID-19 lockdown: a cross-sectional study

BACKGROUND

The emergence of the COVID-19 pandemic has sparked unprecedented global challenges. This study intends to investigate changes in the physical fitness of students aged 6-22 during the COVID-19 pandemic and to assess how the pandemic lockdown period affected these markers.

METHODS

According to the National Student Physical Health Standard, a stratified cluster sampling method was used to evaluate the body shape, body function, and physical fitness of children and adolescents (n = 8092) in Xi'an from 2019 to 2021. This study uses SPSS 26.0 (IBM, Chicago, IL, USA) for data statistics and analysis. The connection between physical fitness and years was measured using the one-variable analysis in the general linear model (GLM). Independent t-tests were used to determine the sex (male/female) and area (urban/rural) differences.

RESULTS

During the lockdown period, Body Mass Index (BMI) and flexibility showed an upward trend, while aerobic, strength, speed, and endurance showed a downward trend. In addition to the BMI of middle and high school students, almost all indicators show significant sex differences. There are urban-rural differences in some indicators, such as chin-ups.

CONCLUSION

During the pandemic of COVID-19, the physical fitness of children and adolescents in Xi'an did not change significantly, and there were slight differences among different grades. During the pandemic lockdown period, lifestyle changes and reduced outdoor activities for children and adolescents may be the reasons for the changing trend of various indicators.

Spatial-temporal evolution of overweight and obesity among Chinese adolescents from 2016 to 2020

This study examines the spatial-temporal evolution of overweight and obesity among Chinese adolescents aged 14-17. Data from five national surveys conducted between 2016 and 2020 were analyzed to determine distribution patterns and trends. Results showed that overweight and obesity exhibit spatial clustering, with greater severity in the north and less severity in the south. The issue has spread from the northeast to the southwest of Mainland China. Using a local autocorrelation model, the regions were divided into a northern disease cold spot area (Inner Mongolia) and a southern disease hot spot area (Guangxi). Over the past five years, overweight rates among Chinese adolescents have not been effectively curbed, but obesity has shown some success in control and reversal until 2019. Future efforts should focus on the spatial-temporal pattern of disease spread, targeting hotspot areas and abnormal values for regional synergy and precise prevention and control.

Trend and heterogeneity in forced vital capacity among Chinese students during 1985-2019: results from Chinese National Survey on Students' Constitution and Health

BACKGROUND

Forced vital capacity (FVC) reflects respiratory health, but the long-term trend and heterogeneity in FVC of Chinese students were understudied.

METHODS

Data were from Chinese National Survey on Students' Constitution and Health 1985-2019. Super Imposition by Translation and Rotation model was used to draw FVC growth curves. Sex-, region-, and nationality-heterogeneity in FVC was evaluated. Spearman correlation and generalized additive model was used to reveal influencing factors for FVC.

RESULTS

Compared to 1985, age at peak FVC velocity was 1.09, 3.17, 0.74, and 1.87 years earlier for urban male, urban female, rural male, and rural female in 2019, respectively. Peak FVC velocity first decreased and then increased during 1985-2019, only male rebounded to larger than 1985 level. FVC declined from 1985 to 2005 and then raised. Males consistently had higher FVC than females, with disparities increasing in the 13-15 age group. Urban students also had higher FVC than rural students. In 2019, FVC difference between 30 Chinese provinces and the national average showed four scenarios: consistently above national average; less than national average until age 18, then above; greater than national average until age 18, then this advantage reversed; less than national average in almost all the age. Most Chinese ethnic minority students had lower FVC levels compared to Han students. Spearman correlation and generalized additive model showed that age, sex, and height were the leading influencing factors of FVC, followed by socioeconomic and environmental factors.

CONCLUSIONS

Chinese students experienced advanced FVC spurt, and there was sex-, region- and nationality-heterogeneity in FVC. Routine measurement of FVC is necessary in less developed areas of China.