Replacement of watching television with physical activity and the change in gestational diabetes mellitus risk: A case–control study.

Objective: To evaluate the effect of replacing 1 h/week of watching television with 1 h/week of light to moderate (LMPA) or vigorous physical activity (VPA) before and during pregnancy on the risk of gestational diabetes mellitus (GDM). Methods: A case–control study was conducted in pregnant women. Physical activity and television watching before and during pregnancy were assessed using the Paffenbarger Physical Activity Questionnaire. Each type of activity was classified according to intensity (metabolic equivalent of task; MET): less than 6 METs is LMPA, 6 METs or more is VPA. The duration of physical activity and watching television was calculated, and logistic regression models were used to estimate adjusted odds ratios (aOR) and 95% confidence intervals for their association with GDM risk. The isotemporal substitution model was used to calculate the effect of replacing 1 h/week of watching television with the same duration of physical activity. Results: The GDM cases (n = 290) spent less time performing VPA than controls without GDM (n = 1175) and more time watching television during pregnancy (P < 0.05). During pregnancy, the risk of GDM increased for each hour of watching television (aOR = 1.02; 95% confidence interval 1.00–1.03). Women who spent more time watching television during pregnancy were likely to develop GDM (aOR>14 h/week vs. 0–6 h/week = 2.03; 95% confidence interval 1.35–3.08). Replacing 1 h/week of watching television with 1 h/week of VPA during pregnancy could decrease the chance of developing GDM (aOR = 0.66; 95% confidence interval 0.43–1.00). Conclusions: A simple change of 1 h/week of watching television for 1 h/week of VPA in pregnant women may reduce the risk of GDM considerably. Synopsis: Substituting 1 h/week of watching television with 1 h/week of vigorous physical activity during pregnancy could reduce gestational diabetes mellitus risk by 34%. [ABSTRACT FROM AUTHOR]