Associations Between Screen-Time and Life Factors of One-Year-Olds: Results From the Largest Japanese Birth Cohort (The Japan Environment and Children's Study [JECS])

Background: The recent increase in the use of electronic media devices has raised concerns about possible adverse health effects of long periods of screen-viewing. The purpose of this study was to assess trends in screen-time and correlated factors in early infancy. Methods: We analysed data of one-year-old children from a large Japanese cohort, the Japan Environment and Children’s Study (JECS), and singletons whose primary caregivers were mothers. Screen-time was defined as the amount of time that mothers chose to have their children watch TV or DVDs per day. We first assessed the data using univariable analysis and then multivariate analysis. We divided the children’s viewing data into two groups: short (0–4 h) and long (≥ 4 h) screen-time groups. Findings: Of the 86938 one-year-old singletons, 8899 ( 10·3% ) had no reported screen-viewing time, while 5517 (6·4%) had more than 4 h per day. Independent variables that were significantly correlated with children’s long screen-time were area of habitation, mother’s media-use time, employment status, and educational background, K6, and mother-infant bonding (anger and rejection, and impaired bonding). Mothers with long durations of media use exhibited the highest odds ratio (OR: 13·26, 95% CI: 11.28–15.60; reference set as children with no screen-time). Interpretation: Major guidelines recommend no screen-time for children under two, although 90% engage in screen-time by the age of one. Factors associated with more screen-viewing time include some life factors of caregivers, especially their prolonged media use as well as relatively high scores for mother’s not-working status. Trial Registration: This study was registered in the UMIN Clinical Trials Registry (UMI30786). Funding: This study was funded by the Ministry of the Environment, Japan. The findings and conclusions of this article are solely the responsibility of the authors and do not represent the official views of the above government. Declaration of Interests: We declare no competing interests. Ethics Approval Statement: Data were extracted from the dataset distributed in March 2018 (jecs-an-20180131) to assess the association between the duration of media use and related factors. The study protocol was approved by the Institutional Review Boards of Epidemiological Studies of the Ministry of the Environment, Japan and by the Ethics Committees of all participating institutions.