Factors Contributing to Screen Exposure in Preschool Children and Its Associated Outcomes: A Systematic Review.

The vast majority of included studies were cross-sectional, meaning they cannot prove that screen time causes developmental delays; children with existing delays may also watch more screens. Most studies measured screen time as a single number (duration), failing to capture critical nuances like content type, context (e.g., co-viewing), or device used. There is a significant asymmetry in the literature, with 93 studies reporting adverse effects versus only 5 reporting positive effects, potentially reflecting publication bias or a deficit-focused research agenda. The review excluded children with neurodevelopmental disorders, so findings may not apply to populations commonly seen in therapy settings. Methodological quality varied, with 35.63% of cross-sectional studies failing to identify or address confounding factors.

The authors declared no conflicts of interest. The work was funded by Fundação para a Ciência e a Tecnologia (Portugal) and the European Social Fund.

Do not interpret the associations as proof that screen time causes developmental delays. The evidence is observational and cross-sectional, so it is also possible that children with early developmental difficulties are given more screen time by parents seeking quiet or stimulation. Additionally, do not assume all screen time is harmful; the review notes that interactive, educational use in a supportive context may have neutral or positive effects.