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 ≥7.8 mmol/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 - 4 h per day and >4 h per day were associated with significantly increased risk of GDM (multivariable OR of sitting time for 2 - 4 h vs <2 h: 1.59, 95% CI: 1.18 - 2.15; OR of sitting time for >4 h vs <2 h: 1.73, 95% CI: 1.22 - 2.43). Conclusions: Increased physical activity during pregnancy was associated with reduced GDM risk, whereas sedentary lifestyle was associated with increased GDM risk among Chinese pregnant women.