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.

Transition From Pediatric to Adult Healthcare for Colorectal Conditions: A Systematic Review.

BACKGROUND: Despite surgical advances for complex congenital colorectal conditions, such as anorectal malformation (ARM) and Hirschsprung disease (HD), many adolescents require transfer from specialist pediatric to adult providers for ongoing care. METHODOLOGY: A systematic review of PubMed, MEDLINE and Embase was conducted to identify what is known about the transitional care of patients with ARM and HD (PROSPERO # CRD42022281558). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework guided our reporting of studies that focused on the transition care of 10-30-year-olds with ARM and HD. RESULTS: Eight studies were identified that included patient and parent (n = 188), and/or clinician perspectives (n = 334). Patients and clinicians agreed that transitional care should commence early in adolescence to support transfer to adult care when a suitable level of maturation is reached. There was little evidence from patients that transfer happened in a timely or coordinated manner. Patients felt that clinicians did not always understand the significance of transfer to adult services. No models of transition care were identified. Surgeons ranked ARM and HD as the most common conditions to experience delayed transfer to adult care. Beyond pediatric surgeons, patients also highlighted the importance of general practitioners, transitional care coordinators and peer support groups for successful transition. CONCLUSIONS: There is little research focused on transitional care for patients with ARM and HD. Given evidence of delayed transfer and poor experiences, the development of models of transitional care appears essential.

Development of an inpatient protocol for adolescents with avoidant/restrictive food intake disorder: a case study.

Introduction: Avoidant/restrictive food intake disorder (ARFID) is an eating disorder characterised by a pattern of eating that leads to failure to meet appropriate nutritional and/or energy needs. Method: In the absence of evidence-based inpatient guidelines for adolescents with ARFID, we set out to develop and pilot an inpatient protocol for adolescents with ARFID. Identification of the key differences between managing inpatients with ARFID and anorexia nervosa (AN) led to modification of an existing AN protocol with the goals of better meeting patient needs, enhancing alignment with outpatient care, and improving outcomes. A case report of an adolescent with ARFID who had three hospital admissions is presented to highlight these changes. Interviews with this patient and her family were undertaken, together with key staff, to explore the challenges of the AN protocol for this patient and the perceived benefits and any limitations of the ARFID protocol for this patient and others. Results: The new ARFID protocol supports greater choice of meals, without the need for rest periods after meals and bathroom supervision. The similarities with the AN protocol reflect the need to promote timely weight gain through meal support, including a staged approach to nutritional supplementation. The protocol appears to have been well accepted by the patient and her family, as well as by staff, and continues to be used in cases of ARFID. Conclusion: Further evaluation would help identify how well this protocol meets the needs of different adolescents with ARFID.

Introduction: Le trouble évitant/restrictif de la prise alimentaire (TERPA) est un trouble alimentaire caractérisé par un modèle d'alimentation qui entraîne une incapacité à répondre aux besoins nutritionnels et/ou énergétiques appropriés. Méthode: En l'absence de lignes directrices fondées sur des données probantes en milieu hospitalier pour des adolescents souffrant de TERPA, nous avons entrepris de développer et de piloter un protocole en milieu hospitalier pour les adolescents souffrant de TERPA. L'identification des principales différences entre la prise en charge des patients hospitalisés souffrant de TERPA et d'anorexie mentale (AM) a mené à une modification d'un protocole d'AM existant dans le but de mieux répondre aux besoins des patients, d'accroître l'alignement avec les soins des patients ambulatoires, et d'améliorer les résultats. Un rapport de cas d'une adolescente souffrant de TERPA qui a eu trois hospitalisations est présenté pour souligner ces changements. Des entrevues avec cette patiente et sa famille ont été réalisées, de même qu'avec le personnel principal, afin d'explorer les difficultés du protocole d'AM pour cette patiente ainsi que les avantages perçus et toute limite du protocole TERPA pour cette patiente et d'autres. Résultats: Le nouveau protocole TERPA supporte un plus grand nombre de repas, sans le besoin de périodes de repos après les repas et une supervision de la salle de bain. Les similitudes avec le protocole AM reflètent le besoin de promouvoir une prise de poids rapide grâce à un soutien aux repas, y compris une approche par étapes de supplémentation nutritionnelle. Le protocole semble avoir été bien accepté par la patiente et sa famille, ainsi que par le personnel, et continue d'être utilisé dans les cas de TERPA. Conclusion: Une évaluation plus poussée aiderait à identifier dans quelle mesure ce protocole répond aux besoins de différents adolescents souffrant de TERPA.

Health-related quality of life and self-reported health status in adolescents with chronic health conditions before transfer of care to adult health care: an international cohort study.

BACKGROUND: Heath-related quality of life (HRQoL) is lower in adolescents with chronic health conditions compared to healthy peers. While there is evidence of some differences according to the underlying condition and gender, differences by measure and country are poorly understood. In this study we focus on the differences in HRQoL in adolescents with various chronic medical conditions in the year before transfer of care to adult health services. We also study the associations of two different HRQoL measurements to each other and to self-reported health. METHODS: We recruited 538 adolescents from New Children`s Hospital, Helsinki, Finland, and the Royal Children`s Hospital, Melbourne, Australia in 2017-2020. We used two validated HRQoL measurement instruments, Pediatric Quality of Life Inventory (PedsQL) and 16D, and a visual analog scale (VAS) for self-reported health status. RESULTS: In total, 512 adolescents (50.4% female, mean age 17.8 [SD 1.2] years), completed the survey measures. Higher HRQoL was reported in males than females in both countries (PedsQL 79.4 vs. 74.1; 16D 0.888 vs. 0.846), and in adolescents from Finland than Australia (80.6 vs. 72.2 and 0.905 vs. 0.825, p < 0.001 for all). Adolescents with diabetes, rheumatological, nephrological conditions and/or organ transplants had higher HRQoL than adolescents with neurological conditions or other disease syndromes (p < 0.001). PedsQL and 16D scores showed a strong correlation to each other (Spearman correlation coefficient r = 0.81). Using the 7-point VAS (1-7), 52% (248 of 479) considered their health status to be good (6-7) and 10% (48 of 479) rated it poor (1-2). Better self-reported health was associated with higher HRQoL. CONCLUSIONS: The HRQoL of transition aged adolescents varies between genders, diagnostic groups, and countries of residence. The association between self-reported health and HRQoL suggests that brief assessment using the VAS could identify adolescents who may benefit from in-depth HRQoL evaluation. TRIAL REGISTRATION: Trial registration name The Bridge and registration number NCT04631965 ( https://clinicaltrials.gov/ct2/show/NCT04631965 ).

Development and validation of the adolescent behavioural change Counselling Assessment Tool in Indonesia.

BACKGROUND: Primary care provides an important context to engage adolescents and their families in healthy lifestyles with the goal of reducing future behaviour-related health problems. Developing a valid tool to assess health professionals' skills in behavioural change counselling is integral to improving the quality of clinical care provided to adolescents in Indonesia. METHODS: This work was nested within a project to develop a training program to enhance the behaviour-change counselling of adolescents and their parents by Indonesian primary care professionals. Initial item development was based on the content of the training module and the domain structure of the Behavioral Change Counselling Index (BECCI), a commonly used tool to assess counselling quality in healthcare settings. Expert panels were used to test content validity, while face validity was assessed by a group of trained psychologists. Inter-rater agreement was calculated prior to tests of construct validity and reliability, which involved psychologists rating 125 audio-taped counselling sessions between the health professional and adolescent patients, together with a parent. RESULTS: An initial 13-item tool was developed using a 1-5 Likert scale. Validity and reliability testing resulted in the decision to use a 14-item tool with a 0-3 Likert scale. The scale was found to have a Cronbach's α coefficient of 0.839 (internal consistency), and there was strong inter-rater agreement (0.931). CONCLUSION: The assessment tool known as the Adolescent Behavioural Change Counselling Assessment Tool, is a valid and reliable instrument to measure Indonesian health professionals' behavioural-change counselling skills with adolescent patients. The tool provides an evaluation framework for future interventions that aim to improve health professionals' skills in addressing adolescent behaviour-related health problems.

Prevalence of Eating Disorder Symptoms in Transgender and Gender Diverse Adolescents Presenting for Gender-Affirming Care.

PURPOSE: To describe the prevalence of eating disorder symptoms among adolescents seeking gender-affirming care. METHODS: Cross-sectional study of 660 gender-diverse adolescents who completed the Branched Eating Disorder Test to measure anorexia and bulimia symptoms. RESULTS: 23.9% (95% CI 20.7-27.4) reported both anorexia symptoms, namely overvaluation of weight and fear of (or recurrent interference with) weight gain. 0.9% (95% CI 0.3-2.0) reported all bulimia symptoms, namely overvaluation of weight, recurrent binge eating, and recurrent compensatory behaviors (e.g., weekly purging). For all symptoms, prevalence was higher among i) adolescents assigned female at birth compared to those assigned male at birth, and ii) adolescents who felt unsure about their gender identity compared to those who identified as trans or nonbinary. DISCUSSION: Clinicians should monitor eating disorder symptoms among adolescents presenting for gender-affirming care, especially among those assigned female at birth or who are unsure about their gender identity.

Characterization of Puberty in an Australian Population-Based Cohort Study.

PURPOSE: Current knowledge of the characteristics of puberty beyond age at menarche and thelarche is limited, particularly within population-based cohorts. Secular trends and concerns of the health effects of early puberty reinforce the value of contemporary studies characterizing the timing, tempo, duration, and synchronicity of puberty. METHODS: The Childhood to Adolescence Transition Study is a unique Australian cohort of individuals followed annually from late childhood to late adolescence, with up to eight assessments of pubertal stage from 9 to 19 years of age (N = 1,183; 636 females). At each assessment, females reported their Tanner Stage of breast and pubic hair development, while males reported on genital/pubic hair development. Nonlinear mixed-effects models characterized pubertal trajectories and were used to derive each individual's estimates of timing, tempo, and synchronicity. Parametric survival models were used to estimate the overall duration of puberty. RESULTS: Timing of mid-puberty (Tanner Stage 3) ranged from 12.5 to 13.5 years, with females developing approximately 6 months before males. Pubertal tempo (at mid-puberty) was similar across sex (between half and one Tanner Stage per year), but the overall duration of puberty was slightly shorter in males. Most females exhibited asynchronous changes of breast and pubic hair development. DISCUSSION: Estimates of pubertal timing and tempo are consistent with reports of cohorts from two or more decades ago, suggesting stabilization of certain pubertal characteristics in predominantly White populations. However, our understanding of the duration of puberty and individual differences in pubertal characteristics (e.g., synchronicity of physical changes) remains limited.

Experiences of Family and Partner Support in Fertility Decision-Making Among Adolescents and Young Adults with Cancer: A National Australian Study.

Purpose: To understand how adolescents and young adults (AYAs) with cancer experience family and partner involvement in fertility preservation (FP) decision-making. Methods: As part of a nationally representative Australian cross-sectional study of 15-25-year olds with cancer, 196 participants (mean age 19.9 [standard deviation 3.2] years at diagnosis; 51% male) were surveyed regarding FP decision-making. Results: One hundred sixty-one (83%) participants reported discussion of potential effects of cancer and its treatment on fertility, of whom 57 (35%) did not undertake FP (51% of females; 19% of males). Parental involvement (mothers 62%, fathers 45%) in decision-making was considered helpful, including for 73% of 20-25-year olds with partners. Sisters and brothers were involved less often, yet rated helpful in 48% and 41% of cases, respectively. Older participants were more likely than younger ones to have involved partners (47% vs. 22%, p = 0.001) and less likely to have involved mothers (56% vs. 71%, p = 0.04) or fathers (39% vs. 55%, p = 0.04). Conclusion: This is the first quantitative study to explore family and partner involvement in AYA FP decision-making in both females and males in a nationally representative sample. Parents are important resources who commonly assist AYAs with these complex decisions. Although many AYAs will be the main decision-makers when it comes to FP, particularly as AYAs mature, these data suggest that resources and support should be available for and inclusive of parents, partners, and siblings.

Experiences of Oncofertility Decision-Making and Care in a National Sample of Adolescent and Young Adult Cancer Patients and Parents.

Purpose: Cancer and its treatments are known to compromise fertility in adolescents and young adults (AYAs). The emotional burden of possible infertility is reduced in those who receive supportive oncofertility care. In legal minors, provision of health care must consider the legal context and desire that AYAs have for autonomous decision-making, together with their competence to make health decisions. This has important implications for how oncofertility discussions may, or may not, involve parents. The aim of this study was to explore oncofertility decision-making and care experiences in a national Australian sample of AYA cancer patients and their parents. Methods: AYAs aged 15-25 years and parents were recruited from 17 cancer care sites and CanTeen Australia as part of a national AYA cancer care study. The cross-sectional survey included open-ended questions regarding oncofertility care experiences. We used reflexive thematic analysis to identify themes. Results: Data were available for 99 AYAs and 111 parents. Four themes were identified: emotional care needs; parent-AYA dynamics including AYA autonomy and agency; decision-making considerations including values and practicalities; and reflections on oncofertility care and follow-up. Both AYAs and parents placed importance on AYA autonomy in fertility decision-making, but many AYAs appreciated the role of parents in providing support and guidance throughout the process. Conclusion: Health care professionals are encouraged to autonomously engage AYAs around fertility decision-making, while concurrently offering opportunities that promote parental support. Better psychological support and follow-up oncofertility care are also needed.

Interpersonal Violence and Gender Inequality in Adolescents: A Systematic Analysis of Global Burden of Disease Data From 1990 to 2019.

PURPOSE: Interpersonal violence is a leading cause of adolescent deaths and disability. This study investigates sex differences in burden of interpersonal violence for adolescents and explores associations with gender inequality. METHOD: Using data from the 2019 Global Burden of Disease study, we report numbers, proportions, rates of interpersonal violence deaths and disability adjusted life years (DALYs) for all ages, and rate of change (from 1990 to 2019) in adolescents aged 10-24 years disaggregated by sex and geography. We explored associations with gender inequality using gender inequality index. RESULTS: One in four (24.8%) all-age interpersonal violence deaths are in adolescents. In 2019, the rate of deaths in adolescent males was almost six times higher than females (9.3 vs. 1.6 per 100,000); and since 1990, the rate of decline in DALYs for females was double than that for males (-28.9% vs. -12.7%). By contrast, the burden of sexual violence is disproportionately borne by adolescent females, with over double the rate than males (DALYs: 42.8 vs. 17.5 per 100,000). In countries with greater gender inequality, the male-to-female ratio (deaths and DALYs) was increased among older adolescents, pointing to benefits for males in more gender equal settings. DISCUSSION: Social identities, relationships, and attitudes to violence are established in adolescence, which is an inflection point marking the emergence of disproportionate burdens of interpersonal violence. Our findings affirm that global agendas must be expanded to address interrelated factors driving multiple forms of interpersonal violence experienced by adolescents and reverberating to the next generation.

Characteristics of Puberty in a Population-Based Sample of Danish Adolescents.

PURPOSE: To describe the duration, timing, tempo, and synchronicity of puberty, as well as the correlation between timing and tempo of puberty. METHODS: Overall, 15,819 of 22,439 invited children participated in the Puberty Cohort within the Danish National Birth Cohort. Participants completed a web-based questionnaire every 6 months through maturation with questions on current pubertal status. Girls reported current Tanner stage of breast and pubic hair development, and timing of menarche. Boys reported current Tanner stage of genital and pubic hair development, timing of first ejaculation, and vocal changes. While accounting for this interval-censored puberty information, we estimated the duration of puberty. Then, we used a nonlinear mixed effect growth model to estimate timing, tempo, synchronicity of puberty, and correlation between timing and tempo of puberty. RESULTS: In girls, the average duration of breast development was longer, whereas the average tempo was slower than pubic hair development. The average timing of breast development was earlier than the average timing of pubic hair development. The majority of girls had asynchronous puberty. In boys, the average duration was longer and average tempo slower for genital than pubic hair development. The average timing of genital and pubic hair development were comparable; hence, the majority had synchronous pubertal development. Adolescents who had earlier timing also tended to have a faster tempo. DISCUSSION: Being one of the largest puberty cohorts worldwide, these unique contemporary data can help physicians, parents, and children to understand and anticipate expected progression through pubertal development.

Development of an internet-based intervention to improve health professionals' counseling skills around adolescent weight management in Indonesia.

BACKGROUND: Obesity is a growing public health and clinical concern, worldwide. In many countries, including Indonesia, health professionals lack the capacity to promote behavior change around obesity prevention and management, especially with adolescents for whom a wider set of communication skills are required. This study describes the theoretical basis, approach to development of content, use and satisfaction of an internet-based educational intervention designed to improve the quality of health professional weight management counseling with adolescents in Indonesia. METHODS: This study is part of an exploratory sequential mixed methods design which was undertaken from 2020 to 2022. Following a needs analysis, an internet-based training resource was developed, informed by constructive alignment theory and active learning principles. Using both synchronous and asynchronous approaches over a four-week pilot study, a weekly interactive session was held online, using multifaceted training materials housed on a website (https://ramahremaja.id). The training resource was then tested in a two-arm study involving health professionals from 17 of 34 provinces across Indonesia. RESULTS: Sixty-four primary health professionals were recruited for the two-arm study. The completion rate for reviewing all materials and assignments on the website was 72% and the online meeting participation rate was 78%. Participants were highly positive about the clarity of the training material and the appropriateness of the delivery methods. The main challenges related to poor internet literacy and interrupted internet connectivity. CONCLUSION: Designed to support weight management in adolescents, this internet-based training program shows potential for enhancing Indonesian health professional behavior-change counseling skills.

Towards responsive policy and actions to address non-communicable disease risks amongst adolescents in Indonesia: insights from key stakeholders.

Background: Non-communicable diseases (NCDs) such as cancer, diabetes, heart disease, mental disorder and chronic lung conditions are the leading cause of death and disability in Indonesia. Adolescence is when risks for NCDs emerge and it is also an important life stage for intervention, yet young people are often at the margins of NCD policy and actions. This study aimed to understand how policies and actions should address NCD risks (tobacco smoking, inadequate physical activity, and diet) for adolescents in Indonesia, and how young people can be meaningfully involved. Methods: Qualitative in-depth interviews over videoconference (n = 21) were conducted in English or Bahasa with stakeholders in Indonesia. Participants included policymakers, implementation partners, and advocates who were focused on adolescent health or NCDs. Interviews were recorded, transcribed, translated, and thematically analysed using NVivo12. Findings were disseminated to participants for validation and feedback. Youth participants (n = 7) attended an additional workshop and considered recommendations and actions arising from this research. Findings: Participants identified that government and non-government organisations are acting on NCDs in Indonesia, but few of the existing initiatives target adolescents, and adolescent services rarely addressed NCD risks. Participants also felt that policies to protect adolescents from NCD risks (i.e., smoke-free areas in public) were not always enforced. For programs or initiatives focused on adolescent health, those that had engaged adolescents as co-creators and leaders were perceived to be more successful. As such, participants recommended more meaningful engagement of young people, including young people's leadership of initiatives. Additional recommendations included the need for intersectoral engagement and a 'whole-of-government' approach to prevention given the complex determinants of NCD risks, and the need for evidence-based actions that are underpinned by quality data to enable monitoring of progress. Interpretation: There is a recognised need to strengthen policies and actions to address NCD risks amongst adolescents in Indonesia. Meaningful youth engagement that allows young people to take the lead, intersectoral actions, and evidence-based data driven responses were key strategies identified. Funding: UNICEF East Asia and Pacific Regional Office.

Immunization Coverage in Young People Experiencing Homelessness and the Impact of a Nurse-led Program.

OBJECTIVES: To identify the proportion of young people experiencing homelessness who are immunized against vaccine-preventable diseases, and to evaluate the impact of a nurse-led immunization program to improve vaccination coverage in this population. METHODS: A retrospective audit of electronic medical records included 400 participants aged 15 to 24 years who had an encounter with the Young People's Health Service, a nurse-led clinic co-located with a specialist youth homelessness service in Melbourne, Australia, between February 2019 and May 2021. RESULTS: Integrating an immunization nurse within a youth specialist homelessness service increased the percentage of young people who were up-to-date with routine vaccinations from 6.0% (n = 24) to 38.8% (n = 155). Intersecting social determinants of health that increased participants' risk of vaccine preventable diseases, and of missing routine vaccines, were common. CONCLUSIONS: Incomplete coverage of routine vaccines is common in young people accessing homelessness services, and this coverage was improved when young people encountered an immunization nurse while accessing support from a specialist youth homelessness service. As a service model, nurse-led community health clinics co-located within homelessness providers can improve vaccination coverage, and therefore health outcomes, of young people experiencing or at risk of homelessness.

The forgotten girls: the state of evidence for health interventions for pregnant adolescents and their newborns in low-income and middle-income countries.

Every year, an estimated 21 million girls aged 15-19 years become pregnant in low-income and middle-income countries (LMICs). Policy responses have focused on reducing the adolescent birth rate whereas efforts to support pregnant adolescents have developed more slowly. We did a systematic review of interventions addressing any health-related outcome for pregnant adolescents and their newborn babies in LMICs and mapped its results to a framework describing high-quality health systems for pregnant adolescents. Although we identified some promising interventions, such as micronutrient supplementation, conditional cash transfers, and well facilitated group care, most studies were at high risk of bias and there were substantial gaps in evidence. These included major gaps in delivery, abortion, and postnatal care, and mental health, violence, and substance misuse-related outcomes. We recommend that the fields of adolescent, maternal, and sexual and reproductive health collaborate to develop more adolescent-inclusive maternal health care and research, and specific interventions for pregnant adolescents. We outline steps to develop high-quality, evidence-based care for the millions of pregnant adolescents and their newborns who currently do not receive this.

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.

BACKGROUND: China's rapid economic growth has brought opportunities for improved health and growth of children and adolescents. We sought to explore the long-term trends and urban-rural inequalities in physical growth (specifically height and BMI) among school-aged children and adolescents in China to identify policy priorities for a healthier generation. METHODS: We used the 1985, 1995, 2005, 2014, and 2019 cycles of the Chinese National Survey on Students' Constitution and Health from primary and secondary schools in 30 mainland provinces, autonomous regions, and municipalities. We analysed height and BMI data for 7, 12, and 18 year old children and adolescents of Han ethnicity. Children and adolescents who had complete data on age, sex, location, weight, and height were included. All surveys used a multi-stage stratified random cluster sampling method and were nationally representative. A univariate kernel density estimation was used to plot the distribution of height and BMI. Quantile regression was used to examine associations between urban and rural locations and the primary outcomes of height and BMI at specific quantiles of distribution (5th, 25th, 50th, 75th, and 95th). FINDINGS: Across the five surveys (in 1985, 1995, 2005, 2014, and 2019), 313 973 children and adolescents were included. From 1985 to 2019, the height and BMI distribution curves shifted to the right for each age group and sex, with the BMI curve becoming more dispersed. Median height in adolescents aged 18 years increased by 3·8 cm (95% CI 3·4-4·1) in boys in urban areas and 5·7 cm (5·3-6·1) in boys in rural areas, and 2·7 cm (2·4-3·0) in girls in urban areas and 3·7 cm (3·4-4·0) in girls in rural areas. Children in urban areas were taller than those in rural areas at every quantile, but the magnitude of this disparity narrowed by 2019. In 2019, the median height of boys in urban areas were 1·4 cm (1·0-1·8) greater in those aged 7 years, 2·5 cm (1·9-3·1) greater in those aged 12 years, and 1·1 cm (0·6-1·5) greater in those aged 18 years than their rural counterparts, whereas the median height of girls in urban areas were 1·1 cm (0·7-1·4) greater in those aged 7 years, 1·6 cm (1·1-2·1) greater in those aged 12 years, and 1·1 cm (0·7-1·5) greater in those aged 18 years than rural girls. Over this period, urban-rural differences in BMI disappeared at the lowest quantile, but persisted at higher quantiles. In 2019, the urban-rural differences in BMI for boys aged 12 years were 0·6 kg/m2 (95% CI 0·3-0·8) at the median, 1·0 kg/m2 (0·6-1·4) at the 75th quantile, and 0·7 kg/m2 (0·1-1·3) at the 95th quantile; for girls aged 12 years, 0·3 kg/m2 (0·1-0·5) at the median, 0·5 kg/m2 (0·2-0·8) at the 75th quantile, and 0·9 kg/m2 (0·3-1·5) at the 95th quantile; for boys aged 18 years, 0·6 kg/m2 (0·4-0·8) at the median, 0·8 kg/m2 (0·5-1·2) at the 75th quantile, and 0.7 kg/m2 (0·0-1·5) at the 95th quantile; and for girls aged 18 years, 0·2 kg/m2 (0·1-0·4) at the median, 0·5 kg/m2 (0·3-0·8) at the 75th quantile, and 1·0 kg/m2 (0·5-1·5) at the 95th quantile. INTERPRETATION: Across three decades, school-aged children and adolescents in China have increased in height and BMI, with less disparity between urban and rural locations. Investments are needed to improve the affordability of healthy foods to help children and adolescents in rural areas reach their potential maximum height. Meanwhile, these changes in BMI necessitate tailored strategies according to urban-rural settings to contain the increase in overweight and obesity and promote optimal growth for children and adolescents. FUNDING: Capital's Funds for Health Improvement and Research, and National Natural Science Foundation of China.