Screen time and developmental health: results from an early childhood study in Canada.

Background: Research has shown that longer hours of screen time are negatively associated with children's healthy development. Whereas most research has focused on school-age children, less is known about this association in early childhood. To fill this gap, we examined the association between screen time and developmental health in preschool-aged children.

Methods: This study draws from a data linkage on children (N = 2983; Mean age = 5.2, SD = 0.3 years, 51% male) in British Columbia (BC), Canada, who entered Kindergarten in public elementary schools in 2019. Parent reports on children's screen time, health behaviors, demographics, and family income collected upon kindergarten entry (09/2019), were linked to teacher reports on children's developmental health, collected halfway through the school year (02/2020). Screen time was assessed with the Childhood Experiences Questionnaire. Developmental vulnerability versus developmental health in five domains (physical, social, emotional, language and cognition, and communication skills) was measured with the Early Development Instrument.

Results: Logistic regression analyses using generalized estimating equation showed that children with more than one hour of daily screen time were more likely to be vulnerable in all five developmental health domains: physical health and wellbeing (odds ratio [OR] =1.41; 95% confidence interval [CI], 0.99 - 2.0; p=0.058), social competence (OR=1.60; 95% CI, 1.16 - 2.2; p=0.004), emotional maturity (OR=1.29; 95% CI, 0.96 - 1.73; p=0.097), language and cognitive development (OR=1.81; 95% CI, 1.19 - 2.74; p=0.006) and communication skills (OR=1.60; 95% CI, 1.1 - 2.34; p=0.015) compared to children reporting up to one hour of screen time/day. An interaction effect between income and screen time on developmental health outcomes was non-significant. Results were adjusted for child demographics, family income, and other health behaviors.

Conclusions: Daily screen time that exceeds the recommended one-hour limit for young children, as suggested by the Canadian 24-h Movement Guidelines for Children and Youth (Tremblay et al. BMC Public Health. 17:874, 2017; Tremblay J Physical Activity Health. 17:92-5, 2020) is negatively associated with developmental health outcomes in early childhood. Screen-based activities should thus be limited for young children. Future research needs to examine the underlying mechanisms through which screen time is linked to developmental vulnerabilities.