Background/Objective: This study investigated the longitudinal association between early fine motor skills and subsequent expressive vocabulary development within Bronfenbrenner’s ecological systems theory. We examined how an abrupt shift in the macrosystem and chronosystem, specifically the COVID-19 pandemic and its associated social restrictions, affected children’s developmental processes within the microsystem of the home and childcare settings. Method: The participants included 1,199 children (pre-pandemic: n = 731; pandemic: n = 468) who attended licensed childcare centers in Japan. Using hierarchical multiple regression analyses adjusted for baseline demographic characteristics and home-rearing environment (HRE), we examined whether fine motor skills at Time 1 (T1) predicted expressive vocabulary outcomes at a two-year follow-up Time 2 (T2), and whether this association differed by cohort. Result: The primary analysis revealed a significant interaction between cohort and fine motor skills at T1 was observed (b = −0.09, p < .001), indicating that the association between early motor skills and later expressive vocabulary differed between the pre-pandemic and pandemic cohorts. These findings suggest that environmental constraints during the pandemic may have disrupted the typical developmental pathways linking motor and linguistic skills. Conclusion: Reduced social interaction and communication opportunities may limit children’s ability to translate motor exploration into language development. This study highlights the sensitivity of developmental processes to broader ecological disruptions.

Background/Objectives: Children’s social development is a significant aspect that supports appropriate behavior in the community, and parents, as the main caregivers, play a central role in developing children’s social skills. However, caregivers experiencing psychological distress – such as depression, anxiety, stress - may find it challenging to provide a nurturing rearing environment. This longitudinal study examined whether caregivers’ baseline mental health predicts children’s social skills 1 year later in an urban Indonesian context. Methods: A one-year follow-up study was conducted in an urban area of Indonesia in 2023–2024, inviting all nine kindergartens in the area to participate. Caregivers completed the demographic and Depression, Anxiety, Stress Scale (DASS-21), while teachers assessed children’s social skills using the Social Skills Scale (SSS). Linear mixed-effects models with random intercepts for kindergarten were estimated to account for clustering. Results: Finally, a total of 270 parent–child dyads were included. After adjusting for baseline social skills and covariates, higher levels of baseline caregiver depression (B = -0.15, p < .001), anxiety (B = -.22, p < .001), and stress (B = -.27, p < .001) were associated with lower children's social skills in the follow-up. Conclusions: Even subclinical variations in caregiver psychological distress may meaningfully influence children’s social development over time. Strengthening caregiver mental health support, particularly in urban communities, may represent an important pathway for promoting early social competence and long-term developmental outcomes.

Background/Objective: Early fine motor skills are consistently associated with later language development, but it remains unclear as to whether this relationship is maintained among children showing early development during the COVID-19 pandemic. In this study, we investigated whether the longitudinal association between early fine motor skills and subsequent vocabulary development differed between children demonstrating early development before and during the COVID-19 pandemic. Method: The participants were 1150 children (pre-pandemic cohort: n = 703; pandemic cohort: n = 447) attending licensed childcare centers in Japan. Hierarchical multiple regression and moderation analyses were conducted to examine whether fine motor skills at Time 1 (T1) predicted vocabulary at Time 2 (T2) after adjusting for baseline vocabulary, demographic characteristics, and home-rearing environment. Results: Fine motor skills at T1 significantly predicted vocabulary at T2 in both cohorts. A significant interaction between cohort and fine motor skills was observed (B = −0.09, p = 0.041), indicating that the strength of this association differed between the pre-pandemic and pandemic cohorts. Children in the latter demonstrated lower vocabulary outcomes across most levels of fine motor proficiency, with cohort differences becoming more pronounced with higher levels of baseline fine motor skills. Conclusions: The findings suggest that the fundamental association between fine motor skills and vocabulary development remained evident despite pandemic-related restrictions; however, changes in children’s social and communicative environments may have reduced opportunities to translate motor competencies into linguistic gains. These results highlight the importance of supportive social interactions and communicative experiences in facilitating early developmental processes.

Background/Objectives: Social interaction may be associated with sleep health, but longitudinal evidence among working-age adults is limited, and ceiling-concentrated scores may complicate linear modeling. We examined baseline social interaction, three-year follow-up sleep quality, and the exploratory role of life satisfaction. Methods: Data came from 487 adults aged 20–58 years surveyed in 2020 and 2023. Social interaction was assessed using the 18-item Index of Social Interaction (ISI). Normal sleep required at least 6 h of sleep and adequate restfulness. Models were adjusted for baseline sleep, demographics, lifestyle, health, depression, and anxiety. The ISI functional form was assessed using natural cubic splines and a piecewise model with a knot at 14. Results: In the initial linear summary model, a higher ISI score was associated with normal follow-up sleep (OR = 1.24, 95% CI: 1.09–1.42). The spline model fit better (likelihood-ratio χ² = 19.69, df = 2, p < 0.001). Below 14, each 1-point increase was associated with higher odds of normal sleep (OR = 2.81, 95% CI: 1.64–4.82); no additional association was observed at 14 or higher (OR = 0.99, 95% CI: 0.83–1.19). The ISI × life satisfaction interaction was sensitive to parameterization. Spline-based analysis showed an average indirect association through life satisfaction (estimate = 0.0077, 95% bootstrap CI: 0.0019–0.0153), while direct and total associations were not significant. ISI was associated with restfulness but not duration. Conclusions: The ISI–sleep association was nonlinear, concentrated in lower scores, and plateaued near the upper end. Life-satisfaction findings were exploratory; concurrent measurement precluded causal mediation inference.

Home-rearing environments are integral to early childhood development. However, it remains unclear whether their developmental significance has changed over time. This study aimed to examine the temporal changes in home-rearing environments and their longitudinal associations with child developmental atypicality in Japan, using baseline assessments from 1999 to 2023 and follow-up assessments through 2024. Data were obtained from the Japanese Childcare Cohort Study, a nationwide childcare-based developmental surveillance project. The analysis included 40,627 1-year observation pairs of 18,210 children enrolled in childcare centers. Home-rearing environments were assessed using the Index of Child Care Environment, and developmental atypicality was evaluated using the Child Development Scale across six domains. Logistic regression models were used to examine the associations between baseline home-rearing environments and developmental atypicality 1 year later, adjusting for baseline developmental status, sex, and age. Generalized additive models and rolling-window analyses were used to assess temporal trends and time-varying associations. Overall, the Index of Child Care Environment scores increased gradually throughout the study period, although social stimulation declined after the mid-2010s. Higher-quality home-rearing environments were generally associated with a lower risk of subsequent developmental atypicality. Protective associations strengthened over time, particularly in the social, communication, vocabulary, and intellectual domains. Home-rearing environments and their developmental implications changed over the 25-year observation period. These findings highlight the continued importance of promoting direct caregiver–child interactions, including shared activities and social engagement. Early childhood surveillance should be periodically re-evaluated to remain relevant to evolving caregiving practices and family contexts.