Prospective Associations Between Screen Media Use and Physical Activity in Preschool Children

Questionnaire-based assessment of typical amount of time per week spent using screen-based media devices during leisure, assessed at two time points. Continuously scaled in main analyses; a difference is computed (18-month follow-up value minus baseline value). Additionally, screen time amount at the two time points will be scaled categorically, according to being classified as low or high according to WHO criteria for preschool children (Low (recommended): \<=1 hour/day, high: \>1 hour/day): High-high, high-low, low-high, and low-low.