Abstract
AIM: To investigate physical activity (PA), sedentary time, and screen time by age, sex, and parental education in a national sample of young children. METHOD: This cross-sectional study, conducted 2021-2024, of Swedish children recruited via their parents, included 1078 children aged 18 months, mean 1.5 ± 0.1 years, and 750 aged four, mean 4.1 ± 0.1 years. PA, sedentary time, and screen time were measured with accelerometry and questionnaire. RESULTS: PA guidelines were met by 94% of the 18-month-old children and 51% of those 4 years old. Among 18-month-old children, 22% met screen time guidelines on weekdays and 17% on weekends; corresponding percentages among children 4 years old were 60% and 28%. Device-measured PA levels were consistently lower for girls than boys at age four, but sex differences were small among 18-month-old children. More children whose parents were highly educated participated in organised activities and used active transport modes; they also had lower screen time than children whose parents had low education. CONCLUSION: Nearly all 18-month-old children met PA guidelines, versus only half of those aged 4 years. Many children in both age groups exceeded screen time guidelines. Age, sex, and parental education were associated with children's PA and screen time, suggesting targeted interventions.