Physical activity, sedentary behaviors and risk of gestational diabetes mellitus: a population-based cross-sectional study in Tianjin, China

Objective Physical activity in a nonpregnant state or before pregnancy reduces the risk of type 2 diabetes and is also associated with reduced risk of gestational diabetes mellitus (GDM). However, it is uncertain whether physical activity during pregnancy reduces the risk of GDM. Design and methods Using an established universal screening system in Tianjin, China, we prospectively recruited 11 450 pregnant women within the 12th gestational week from 2010 to 2012. These women underwent a 50-g 1-h glucose challenge test (GCT) at 24–28 weeks of gestation and a 75-g 2-h oral glucose tolerance test if GCT glucose ≥7.8mmol/L. GDM was defined according to the International Association of Diabetes and Pregnancy Study Group’s criteria. Self-reported physical activity in the last month was collected at GCT time using a validated questionnaire. Results GDM developed in 7.3% (n=840) of the women. Women with GDM were less likely to be engaged in moderate-to-high physical activity during pregnancy than those without (79.8% vs 81.6%, P=0.191). Moderate-to-high physical activity during pregnancy was associated with decreased risk of GDM (multivariable odds ratio (OR): 0.81, 95% confidence interval (CI): 0.67–0.97). Sitting at home for 2–4h per day and >4h per day were associated with significantly increased risk of GDM (multivariable OR of sitting time for 2–4h vs 4h vs