The interaction between mothers and young children is a highly dynamic process neurally characterized by inter-brain synchrony (IBS) at θ and/or α rhythms. However, their establishment, dynamic changes, and roles in mother-child interactions remain unknown. In this study, through a simultaneous dynamic analysis of inter-brain EEG synchrony, intra-brain EEG power, and interactive behaviors from 40 mother-preschooler dyads during turn-taking cooperation, we constructed a dynamic inter-brain model that θ-IBS and α-IBS alternated with interactive behaviors, with EEG frequency-shift as a prerequisite for IBS transitions. When mothers attempt to track their children's attention and/or predict their intentions, they will adjust their EEG frequencies to align with their children's θ oscillations, leading to a higher occurrence of the θ-IBS state. Conversely, the α-IBS state, accompanied by the EEG frequency-shift to the α range, is more prominent during mother-led interactions. Further exploratory analysis reveals greater presence and stability of the θ-IBS state during cooperative than non-cooperative conditions, particularly in dyads with stronger emotional attachments and more frequent interactions in their daily lives. Our findings shed light on the neural oscillatory substrates underlying the IBS dynamics during mother-preschooler interactions.

Human attachment is distinguished by enduring internalized representations that shapes neurodevelopment and social-emotional functioning. However, as unobservable inner processes mixed with social cues and partner-specific factors, the neurocognitive mechanisms of these representations during real-time interaction remain unclear. Using a novel Remote Partner-Belief Manipulation paradigm in 40 child-mother-stranger trios, we experimentally isolated attachment representations in 3-4-year-olds by manipulating children's partner-belief during remote cooperation. The inner processes were captured from synchrony between partners' EEG, showing that children's mother-partner belief, regardless of the actual partner, significantly enhanced interbrain synchrony. This partner-belief modulation concentrated on children's P4 channel (overlaying the attachment-designated right temporoparietal junction), where synchrony strength correlated to attachment security and children's response acceleration due to mother-partner belief. These findings established attachment representations as an independent, endogenous driver of interbrain synchrony, potentially via children's heightened attention towards their attachment figure, implying the role of symbolic attachment activation when separation.

Background:Early childhood development (ECD) programs refer to policies and programs aimed at protecting young children's rights to achieve their full potential. Parenting interventions are effective at improving children's cognitive development and overall well-being. However, there is limited evidence on how to effectively implement and integrate such programs into routine service delivery at scale. The Government of China launched the ECD program in 2013 and the ECD scale-up program in 2023. Objective:Our study aims to design, implement, and evaluate an enhanced ECD program embedded in the primary health care system in order to provide ECD policy recommendations for future national scale-up. Methods:This study involves a multicenter cluster randomized controlled superiority trial in 3 counties with different levels of socioeconomic development in China. Fifty-eight clusters will be randomly assigned in a 1:1 ratio to intervention and control groups, stratified by county. In each cluster, 18 families with children aged 6-23 months will be recruited. Our intervention aims to implement an enhanced ECD program in primary care facilities. Intervention group participants will receive usual care alongside enhanced ECD services, including improved facilities, capacity building, and improved ECD services (age-adapted clinical consultations on nutrition and stimulation, age-specific parenting group sessions, home visits, and referrals for children in need). Moreover, an electronic data platform will be used. Control group participants will receive usual care. Our primary outcome is children's overall development, as measured by the Global Scale of Early Development combined form at 12 months of follow-up. Evaluation data will be collected in both arms. Additionally, a process evaluation and an incremental cost-effectiveness analysis will be conducted. Primary analysis will follow the intention-to-treat principle, and it will use generalized estimating equations to assess the population average intervention effect, with adjustment for corresponding baseline outcomes, selected individual variables, county, cluster variables, and variables differing at baseline. Qualitative data will be collected through semistructured interviews and focus groups, guided by the Capability, Opportunity, Motivation, and Behavior framework to explore implementation-related factors. Data will be transcribed for analysis using NVivo 14 (Lumivero). Ethical approval has been obtained from the Institutional Review Board of Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine. Results:This study was funded in 2023 and registered in April 2024. The recruitment of 1044 participants was completed on September 14, 2024. Data collection was completed on January 31, 2026. Conclusions:We aim to design an enhanced ECD service delivery model that can be embedded into the routine primary health care system. The study findings will guide government policies and reforms for strengthening the health system to scale up ECD services. Furthermore, this project may provide policy evidence to support countries in establishing or expanding their ECD services.

Background The divorce rate has increased globally and in China. Literature from developed countries and few developing countries has shown the negative impact of parental divorce on children’s health and development. This cross-sectional study aimed to examine the association between parental divorce and early childhood development (ECD) in China.Method This study used data collected from four provinces in China and reported by parents or other caregivers of 62 899 children, aged 3–5 years old, in 2017 and 2018. We constructed three types of ECD outcomes: (1) overall score of the early Human Capability Index (eHCI), (2) score of each domain of the eHCI, and (3) a dichotomous variable indicating a child developmentally on track, defined by ranking above the 20th percentile of overall eHCI scores in the corresponding age group in the pooled dataset. To understand the link between parental divorce and ECD outcomes, we used the propensity score matching method to match children from divorced families to those from intact families. We applied generalised linear regression models in data analysis using both the full sample and matched sample.Results A total of 3.8% (N=2409) of young children came from divorced families. Children whose parents divorced had significantly lower overall eHCI scores (OR: 0.95, 95% CI 0.92 to 0.98) and lower odds of being developmentally on track (OR: 0.79, 95% CI 0.71 to 0.89), compared with their counterparts after matching. Statistically significant differences were observed in nearly all of nine domains of eHCI, especially for physical health, reading and social and emotional skills. Subgroup analyses showed more prominent associations in Shanghai.Conclusion Children from divorced families showed slower early sociopsychological and physical development than their peers. Efforts are needed to help this vulnerable group minimise the differences.

To assess the neurodevelopment of children under three years, a multinational team of subject matter experts (SMEs) led by the World Health Organization (WHO) developed the Global Scales for Early Development (GSED). The measures include (1) a caregiver-reported short form (SF), (2) a directly administered long form (LF), and (3) a caregiver-reported psychosocial form (PF). The feasibility objectives of this study in Bangladesh, Pakistan, and the United Republic of Tanzania were to assess (1) the study implementation processes, including translation, training, reliability testing, and scheduling of visits and (2) the comprehensibility, cultural relevance, and acceptability of the GSED measures and the related GSED tablet-based application (app) for data collection for caregivers, children, and assessors. In preparation for a large-scale validation study, we implemented several procedures to ensure that study processes were feasible during the main data collection and that the GSED was culturally appropriate, including translation and back translation of the GSED measures and country-specific training packages on study measures and procedures. Data were collected from at least 32 child-caregiver dyads, stratified by age and sex, in each country. Two methods of collecting inter-rater reliability data were tested: live in-person versus video-based assessment. Each country planned two participant visits: the first to gain consent, assess eligibility, and begin administration of the caregiver-reported GSED SF, PF, and other study measures and the second to administer the GSED LF directly to the child. Feedback on the implementation processes was evaluated by in-country assessors through focus group discussions (FGDs). Feedback on the comprehensibility, relevance, and acceptability of the GSED measures from caregivers was obtained through exit interviews in addition to the FGD of assessors. Additional cognitive interviews were conducted during administration to ensure comprehension and cultural relevance for several GSED PF items. The translation-back translation process identified items with words and phrases that were either mistranslated or did not have a literal matching translation in the local languages, requiring rewording or rephrasing. Implementation challenges reiterated the need to develop a more comprehensive training module covering GSED administration and other topics, including the consent process, rapport building, techniques for maintaining privacy and preventing distraction, and using didactic and interactive learning modes. Additionally, it suggested some modifications in the order of administration of measures. Assessor/supervisor concurrent scoring of assessments proved to be the most cost-effective and straightforward method for evaluating inter-rater reliability. Administration of measures using the app was considered culturally acceptable and easy to understand by most caregivers and assessors. Some mothers felt anxious about a few GSED LF items assessing motor skills. Additionally, some objects from the GSED LF kit (a set of props to test specific skills and behaviors) were unfamiliar to the children, and hence, it took extra time for them to familiarize themselves with the materials and understand the task. This study generated invaluable information regarding the implementation of the GSED, including where improvements should be made and where the administered measures’ comprehensibility, relevance, and acceptability needed revisions. These results have implications both for the main GSED validation study and the broader assessment of children’s development in global settings, providing insights into the opportunities and challenges of assessing young children in diverse cultural settings.

Physical punishment without maltreatment is still a common practice worldwide. However, there is a dearth of prospective evidence on the effects of physical punishment on children’s physical outcomes. Data were derived from a 3-year cohort study of a representative sample of 3–6 years old Chinese children (n = 16715). Caregivers reported the usage of physical punishment, history of maltreatment, children’s physical health status (including recurrent sickness, general physical health status, and global sleep disturbance) and two measures of medical service utilization. A propensity score weighted model was used to evaluate the effects of physical punishment on physical health outcomes. Physical punishment without maltreatment was associated with higher risk of recurrent sickness (OR = 1·15, 95

Subtropical and tropical high-density cities are increasingly facing threats of humid heat and associated health issues under global warming. However, the nonlinear impact of humid heat on sleep health remains inadequately understood. This study utilizes data from Guangdong Province, China, and focuses on the often-neglected group of school-age children. Natural cubic spline (NCS) method is employed to assess the nonlinear impacts of humid heat exposures (air temperature (T), wet bulb temperature (W), Humidex (H)) on their sleep health. The exposure-disorder association curves indicate that humid heat is associated with significant increases of risks regarding sleep cycle and nighttime sweating, especially at mild and extreme levels. The relative risks (RRs) for the overall sleep disorder (SD) range from 1.146 (95 % CI: 1.032, 1.271) to 1.172 (1.062, 1.293) at the 50th percentile (T of 27.2 °C, W of 23.6 °C, and H of 36.8 °C). At the 99th percentile (T of 33.4 °C, W of 28.1 °C, and H of 46.4 °C), the RRs increase to between 1.249 (1.075, 1.450) and 1.353 (1.123, 1.629). Compared to traditional climate indicators, it is discovered that compound indicators better reveal the health impacts of high levels of humid heat exposure, highlighting incorporating humidity in health studies in these areas. Moreover, this study presents evidence and reveals that academic pressures heighten school-age children's vulnerability to humid heat, which cannot be mitigated by improving residential environments alone. Tailored strategies include enhancing thermal comfort in exercise areas and improve green spaces in neighborhoods and on campus.

Evidence on the association between ambient ozone (O3) exposure and attention-deficit/hyperactivity disorder (ADHD) in children was limited and inconsistent. To address this gap, we conducted a large-scale study involving 179,661 school-aged children across 14 cities in three regions of China between 2012 and 2018. ADHD symptoms were assessed using parent-reported Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria. A well-validated spatiotemporal model at 1 × 1 km resolution was employed to estimate four-year average O3 concentrations at each participant's home and school addresses. We applied generalized linear mixed models adjusted for a range of potential confounders to examine the associations and explore potential effect modifiers. The prevalence of ADHD symptoms was 5.8 %. Higher O3 exposure was positively associated with ADHD symptoms. Specifically, the odds ratio of ADHD symptoms was 1.24 times greater (95 % confidence interval [CI]: 1.21, 1.26) per interquartile range (7.0 µg/m3) increment in home-school O3 concentration. The association was similar after adjustment for other air pollutants and greenness, as well as in sensitivity analyses. Notably, regional heterogeneity was observed, with a stronger association in the southeastern region. Additionally, larger estimates of O3 were found among older children and those exposed to low temperature, low humidity, and low greenness. Our findings from the largest study in China to date provide compelling evidence that long term exposure to O3 is associated with an increased risk of ADHD symptoms in children, highlighting the need for public health policies to mitigate O3 pollution for the protection of child neurodevelopment.

Background Developmental delay(DD)poses challenges to children's overall development,necessitating early detection and intervention.Existing screening tools in China focus mainly on children with developmental issues in two or more domains,diagnosed as global developmental delay(GDD).However,the recent rise of early childhood development(ECD)concepts has expanded the focus to include not only those with severe brain development impairments but also children who lag in specific domains due to various social-environmental factors,with the aim of promoting positive development through active intervention.To support this approach,corresponding screening tools need to be developed. Methods The current study used a two-phase design to develop and validate the Parent-Reported Indicator of Developmental Evaluation for Chinese Children(PRIDE)tool.In Phase 1,age-specific milestone forms for PRIDE were created through a survey conducted in urban and rural primary care clinics across four economic regions in China.In Phase 2,PRIDE was validated in a community-based sample.Sensitivity and specificity of both PRIDE and Ages and Stages Questionnaires(ASQ)-3 were estimated using inverse probability weights(IPW)and multiple imputation(MI)to address planned and unplanned missing data. Results In Phase 1 involving a total of 1160 participants aged 1 to 48 months,63 items were selected from the initial item pool to create 10 age-specific PRIDE forms.Our Phase 2 study included 777 children within the same age range.PRIDE demonstrated an estimated sensitivity and specificity of 83.3％[95％confidence interval(CI):56.8％-100.0％]and 84.9％(95％CI:82.8％-86.9％)in the identification of DD. Conclusion The findings suggest that PRIDE holds promise as a sensitive tool for detecting DD in community settings.

Advancements in wearable device technology have enabled accelerometers to continuously record minute-by-minute physical activity over consecutive days, yielding curves serially correlated in dense and regular longitudinal design. Motivated by a large-scale cohort of physical activity data throughout a week, the collected repeatedly measured functional data exhibits longitudinal (interday) and functional (intraday) interactions on fine grids. To accommodate this complex data structure and investigate the relationship between health assessment results and weekly physical activity patterns, we propose an innovative and efficient two-dimensional functional mixed-effect model (2dFMM), characterizing the longitudinal and functional cross-variability while incorporating two-dimensional fixed effects and four-dimensional correlation structure in marginal representation. We develop a fast three-stage estimation procedure to provide accurate fixed-effect inference for model interpretability and improve computational efficiency when encountering large datasets. We find strong evidence of intraday and interday varying significant associations between physical activity and mental health assessments among our cohort population, which sheds light on possible intervention strategies targeting daily physical activity patterns to improve school adolescent mental health. Our method is also used in environmental data to illustrate the wide applicability.

STUDY OBJECTIVES:Prosocial behaviors in early childhood predicts future mental health and academic achievements, and its development relies on socio-emotional cognition, such as capacity of cognitive empathy. Vital for early brain development, several studies have revealed the relations between early childhood sleep and prosocial behaviors, while the underlying mechanism remains unexplored. The current study aims to investigate the sleep-prosocial association in a large preschool population, and examined the mediative role of cognitive empathy. METHODS:In this population-based study, a representative sample of 23,524 preschoolers (Mage = 4.29 ± 0.29 years, 48.8 % girls) were recruited in the Shanghai Children's Health, Education and Lifestyle Evaluation-Preschool (SCHEDULE-P) study. Caregivers reported on children's sleep, prosocial behaviors, and cognitive empathy via the Children's Sleep Habits Questionnaire (CSHQ), the Strengths and Difficulties Questionnaire (SDQ), and the Griffith Empathy Measure (GEM), respectively. Logistic regression and mediation model were applied to analyze the sleep-prosocial associations and mediative role of cognitive empathy. RESULTS:The prevalence of prosocial problems was 11.3 % based on parental reports. The mean nighttime sleep duration (NSD) was 9.7 ± 0.7 h. And the prevalence of general sleep disturbances (CSHQ > 48) was 28.2 %. Shorter NSD (aOR = 0.88, p < 0.001) and more general sleep disturbances (aOR = 1.27, p < 0.001) were associated with higher odds of prosocial behavior problems, and the association was robust in most specific sleep problems. Cognitive empathy partially mediated the associations between both NSD (effect = 32.97 %) and general sleep disturbances (effect = 21.05 %) with prosocial behaviors. CONCLUSION:Promoting sleep health and cognitive empathy development in preschoolers with sleep problems may facilitate cognitive empathy development, thereby enhancing prosocial behaviors.

Children now are facing an increasing risk of early life stress (ELS), which leads to detrimental psychosocial outcomes. Behavior studies suggested that positive parental interactions might moderate the negative impact of ELS, but the related biological alteration remains unclear. This study aims to investigate whether positive parent–child interactions moderate the association between maltreatment (as a severe form of ELS) and hair cortisol concentration (HCC), as well as between HCC and psychosocial outcomes in young children. Participants were 6-year-old Chinese children (N = 257, Mage = 6.2, 121 were male) selected by stratified cluster random sampling from a Shanghai population representative cohort. Proximal 3 cm hair strands were analyzed using liquid chromatography coupled with tandem mass spectrometry for HCC. Children’s psychosocial outcome was evaluated using the parental report Strengths and Difficulties Questionnaire (SDQ). Parents also reported the frequency of positive parent–child interactions using the Chinese Parent–Child Interaction Scale (CPCIS) as well as the history of maltreatment. Multi-level logistic regression models adjusting for individual, kindergarten, and district confounders were used to evaluate the associations between maltreatment, HCC, and psychosocial outcomes. Interactions terms tested whether more frequent positive parent–child interactions moderates the association between maltreatment and HCC, as well as between HCC and psychosocial outcomes. Maltreated children exhibited higher levels of HCC (B = 1.20, 95

During the first wave of the COVID-19 pandemic, Shanghai implemented lockdown measures to stop transmission of the virus. Over 26 million residents, including 0.8 million children aged 3-6, were confined at home. This study leveraged a city-wide cohort of preschool children - the Shanghai Children's Health, Education and Lifestyle Evaluation, Preschool (SCHEDULE-P) - and used a quasi-experimental design to study the impact of lockdown on preschool children's mental health and changes in their home environment and lifestyles. Two cohorts - the pre-pandemic cohort and the pandemic cohort - were investigated and compared using the difference-in-differences approach. The Strengths and Difficulties Questionnaire was used to screen children who were at risk for mental health distress. The Index of Childcare Environment questionnaire was used to evaluate the quality and quantity of stimulation and support available to children in their family environment. Children's screen time, sleep duration, and household socioeconomic status were also queried. The results showed that having experienced lockdown and home confinement was associated with a 3.1% increase in the percentage of children at risk for mental health distress, was associated with 21.2 minutes/day longer screen time, 15.7 minutes/day longer sleep duration, and a less favorable family environment. Children of parents with lower levels of education were more likely to experience mental health challenges associated with the lockdown.

From January 24, 2020, to March 24, 2020, during the first wave of the COVID-19 pandemic, Shanghai implemented lockdown measures to stop transmission of the virus. Over 26 million residents, including 0.8 million children aged 3-6, were confined at home. The present study leveraged a city-wide cohort study of preschool children in Shanghai-the Shanghai Children's Health, Education and Lifestyle Evaluation, Preschool (SCHEDULE-P) study-and used a quasi-experimental design to study the impact of lockdown on preschool children's mental health and changes in their home environment and lifestyles. Two cohorts-the pre-pandemic cohort and the pandemic cohort-were investigated and compared using the difference-in-differences estimation framework. The Strengths and Difficulties Questionnaire was used to screen children who were at risk for mental health distress. The Index of Child Care Environment questionnaire was used to evaluate the quality and quantity of stimulation and support available to children in their family environment. Children's screen time, sleep duration, and household socioeconomic status were also queried. All measures were reported by parents. The results showed that having experienced lockdown and home confinement was associated with a 3.1% (95% confidence interval [CI]: 1.9% to 4.4%) increase in the percentage of children at risk for mental health distress, was associated with longer screen time (21.2 min/day, 95% CI: 17.8-24.6), longer sleep duration (15.7 min/day, 95% CI: 14.0, 17.4), and a less favorable family environment. Children of parents with lower levels of education were more likely to experience mental health challenges associated with the lockdown. The study was limited by relying on parents as informants for measuring the key variables. Since both parents and children experienced lockdown, this hindered our ability to isolate the impact of lockdowns solely on children. In summary, the study provides evidence on the influence of lockdown measures on mental health and well-being among young children. Authorities need to manage the risks and consider long-term consequences when issuing measures to contain COVID-19 transmission.

With the rapid development of wearable device technologies, accelerometers can record minute-by-minute physical activity for consecutive days, which provides important insight into a dynamic association between the intensity of physical activity and mental health outcomes for large-scale population studies. Using Shanghai school adolescent cohort we estimate the effect of health assessment results on physical activity profiles recorded by accelerometers throughout a week, which is recognized as repeatedly measured functional data. To achieve this goal, we propose an innovative two-dimensional functional mixed-effect model (2dFMM) for the specialized data, which smoothly varies over longitudinal day observations with covariate-dependent mean and covariance functions. The modeling framework characterizes the longitudinal and functional structures while incorporating two-dimensional fixed effects for covariates of interest. We also develop a fast three-stage estimation procedure to provide accurate fixed-effect inference for model interpretability and improve computational efficiency when encountering large datasets. We find strong evidence of intraday and interday varying significant associations between physical activity and mental health assessments among our cohort population, which shed light on possible intervention strategies targeting daily physical activity patterns to improve school adolescent mental health. Our method is also used in environmental data to illustrate the wide applicability. Supplementary materials for this article are available online.

Mother-child interaction is a highly dynamic process neurally characterized by inter-brain synchrony (IBS) at θ and/or α rhythms. However, their establishment, dynamic changes, and roles in mother-child interactions remain unknown. Through dynamic analysis of dual-EEG from 40 mother-child dyads during turn-taking cooperation, we uncover that θ-IBS and α-IBS alternated with interactive behaviors, with EEG frequency-shift as a prerequisite for IBS transitions. When mothers attempt to track their children's attention and/or predict their intentions, they will adjust their EEG frequencies to align with their children's θ oscillations, leading to a higher occurrence of the θ-IBS state. Conversely, the α-IBS state, accompanied by the EEG frequency-shift to the α range, is more prominent during mother-led interactions. Further exploratory analysis reveals greater presence and stability of the θ-IBS state during cooperative than non-cooperative conditions, particularly in dyads with stronger emotional attachments and more frequent interactions in their daily lives. Our findings shed light on the neural oscillational substrates underlying the IBS dynamics during mother-child interactions.

Despite rapid economic growth in China since 1978, rural-urban inequality has widened. High levels of socioeconomic inequality can have profound implications for child development and lifelong educational equity. Using a dataset containing early childhood development (ECD) outcomes of 0- to 3-year-olds (N = 9,053) from study sites in Eastern, Central, and Western China, the study finds that the risks of cognitive, language, and motor delay are, respectively, 43.2, 18.3, and 20.7 percentage points higher in rural study sites than in urban Shanghai (ps < .01). Impact evaluation of cluster-randomized experiments shows that parental training (focusing on child psychosocial stimulation and caregiver-child interaction) can improve parenting beliefs and practices (or investments) and ECD outcomes of disadvantaged rural children (p<.01). Such programs can play an important role in advancing progress toward more social equality and economic equity, the stated goals of China’s “Common Prosperity” policy.

This cohort study examines the risk of mental health problems associated with consumption of educational, entertainment, and non-child-directed programs as well as electronic games and social media in children aged 3 to 6 years. Key PointsQuestionWhat are the associations between screen exposure to different content types and mental health in children aged 3 to 6 years? FindingsIn this cohort study of 15965 kindergarten children, screen exposure was consistently associated with risk for mental health problems, but the associations varied by content type. Specifically, under a given total screen time, children with a higher proportion of screen exposure to educational programs had a lower risk for mental health problems, whereas the non-child-directed programs were associated with a higher risk for such problems. MeaningFindings of this study suggest that both screen time and on-screen content matter for children's mental health. ImportanceExcessive screen time has been associated with a higher risk for mental health problems, but whether the associations differ by screen content types is unclear. ObjectiveTo examine the allocation of and longitudinal changes in screen exposure across different content types and to explore their associations with mental health in children aged 3 to 6 years. Design, Setting, and ParticipantsThis cohort study used 3-wave, lagged generalized estimating equation models to analyze data from the Shanghai Children's Health, Education and Lifestyle Evaluation-Preschool (SCHEDULE-P) study in Shanghai, China. The cohort was a representative sample of kindergarten children. Data were collected between November 2016 and May 2019 when children were aged 3 to 4 years (wave 1), 4 to 5 years (wave 2), and 5 to 6 years (wave 3). Data analysis was performed between June 2022 and May 2023. ExposureScreen exposure (total daily time and time with each type of content, including educational programs, entertainment programs, non-child-directed programs, electronic games, and social media) was collected when children were aged 3, 5, and 6 years. Main Outcomes and MeasuresMental health of children at age 3, 5, and 6 years was reported by parents using the Strengths and Difficulties Questionnaire. ResultsOf the 15965 children included in the representative sample, 8270 were males (51.7%) and the mean (SD) age at wave 1 was 3.73 (0.30) years. As children developed from ages 3 to 6 years, the proportion of screen exposure to educational programs (<= 1 hour per day: 45.0% [95% CI, 43.5%-46.5%] to 26.8% [95% CI, 25.3%-28.3%]) and entertainment programs (<= 1 hour per day: 44.4% [95% CI, 42.8%-45.9%] to 32.1% [95% CI, 30.4%-33.9%]) decreased, whereas exposure to social media increased (<= 1 hour per day: 1.5% [95% CI, 1.2%-1.9%] to 27.1% [95% CI, 25.5%-28.7%]). The associations between on-screen content and mental health varied. For a given total screen time, a higher proportion of screen exposure to educational programs was associated with a lower risk for mental health problems (adjusted odds ratio [AOR], 0.73; 95% CI, 0.60-0.90), whereas non-child-directed programs were associated with a higher risk for such problems (AOR, 2.82; 95% CI, 1.91-4.18). Regardless of the content, total screen time was consistently associated with mental health problems. Conclusions and relevanceResults of this study indicated that both total screen time and different types of content were associated with mental health problems in children aged 3 to 6 years. Limiting children's screen time, prioritizing educational programs, and avoiding non-child-directed programs are recommended.

Children's exposures to environmental antibiotics are a major public health concern. However, limited data are available on the effects of environmental antibiotic exposures on childhood obesity. Our study aimed to explore this relationship. We conducted a cross-sectional case-control study nested in a population-based survey of primary school students, including 1855 obese and 1875 random selected control children. A total of 10 antibiotics in urine samples were measured by liquid chromatography-tandem mass spectrometry. Multivariable survey logistic regression was used to assess the associations between environmental antibiotics exposures and childhood obesity. After adjusting for potential confounders, increased odds of obesity were observed in children exposed to tetracycline (OR = 1.31, 95% CI: 1.09-1.57) and sulfamonomethoxine (OR = 1.43, 95% CI: 1-2.05). Comparing none (<LODs), low-, middle-, and high-exposure groups, the low- sulfamonomethoxine exposure was associated with an increased odds of obesity (OR = 1.91, 95% CI: 1.05-3.47). Higher odds of obesity were associated with middle-level exposures to tetracycline (OR = 1.96, 95% CI: 1.05-3.66), doxycycline (OR = 1.56, 95% CI: 1-2.46), and lincomycin (OR = 1.35, 95% CI: 1.05-1.74). However, no significant association was found in any high-level antibiotic exposure groups. The significant associations were mainly observed in boys. The associations between environmental antibiotics exposures and childhood obesity are non-linear. Low- to middle-level exposures to certain environmental antibiotics may increase the risk of childhood obesity, especially in boys.