Sex-specific longitudinal associations of screen viewing time in children at 2-3 years with adiposity at 3-5 years

Objectives Screen-viewing in late childhood has been associated with adiposity and blood pressure (BP), but evidence is lacking at younger ages. To investigate the prospective associations of total and device-specific screen-viewing at age 2-3 years with BMI, sum of skinfold thicknesses and BP among Singaporean children at age 3-5 years. Methods As part of the Growing Up in Singapore Towards healthy Outcomes (GUSTO) cohort, mothers/caregivers reported the time per day their 2 and 3-year-old children watched/used television, handheld devices and computers. Average screen-viewing time (total, television and handheld-devices) at ages 2 and 3 years was used in the analyses. Height; weight; triceps, biceps and subscapular skinfold thicknesses; and systolic and diastolic BP were measured at ages 3, 4 and 5. Associations of screen-viewing with BMI, sum of skinfold thicknesses and BP in 956 children were investigated using repeated-measures linear regression models. Analyses were further stratified by sex as we found significant interaction. Results Among boys and girls combined, screen-viewing was positively associated with sum of skinfold thicknesses, but not with BMI or BP. Sex-specific analyses showed significant associations with both BMI and sum of skinfold thicknesses in boys, but not in girls. Screen-viewing was not associated with BP in boys or girls. The increases in mean (95% CI) BMI per hour increase in daily total, television and handheld-devices screen-viewing among boys were 0.12 (0.03, 0.21), 0.18 (0.06, 0.30) and 0.11 (-0.07, 0.29) kg/m(2), respectively. The corresponding increases in mean sum of skinfold thicknesses were 0.68 (0.29, 1.07), 0.79 (0.26, 1.32) and 1.18 (0.38, 1.99) mm. Conclusions Greater screen-viewing at age 2-3 years was associated with later adiposity at 3-5 years in boys, but not in girls. In light of the increasing use of screen devices and cardiometabolic risk in young children, these findings may have important public health implications.