Associations of physical activity and inactivity before and during pregnancy with glucose tolerance.

OBJECTIVE: To investigate associations of physical activity and television viewing before and during pregnancy with risk of gestational diabetes mellitus (GDM) and abnormal glucose tolerance, the combination of GDM with less severe impaired glucose tolerance.
METHODS: We assessed duration and intensity of physical activity and time spent viewing television both before and during pregnancy among 1,805 women enrolled in Project Viva, a cohort study in eastern Massachusetts. We identified 1,493 (83%) women with normal glucose tolerance and 312 (17%) with abnormal glucose tolerance, including 91 (5%) with GDM based on clinical glucose tolerance test results.
RESULTS: After adjustment for age, race or ethnicity, history of GDM, family history of diabetes, and prepregnancy body mass index, our data suggest that women who engaged in any vigorous physical activity in the year before pregnancy experienced a reduced risk of GDM (odds ratio [OR] 0.56, 95% confidence interval [CI] 0.33-0.95) and abnormal glucose tolerance (OR 0.76, 95% CI 0.57-1.00). Women who reported vigorous activity before pregnancy and light-to-moderate or vigorous activity during pregnancy appeared to have a lower risk of both GDM (OR 0.49, 95% CI 0.24-1.01) and abnormal glucose tolerance (OR 0.70, 95% CI 0.49-1.01) compared with women reporting these activities in neither time period. Walking and total physical activity provided modest benefits. We observed no association of television viewing before or during pregnancy with risk of GDM or abnormal glucose tolerance.
CONCLUSION: Physical activity, especially vigorous activity before pregnancy and at least light-to-moderate activity during pregnancy, may reduce risk for abnormal glucose tolerance and GDM. LEVEL OF EVIDENCE: II-2.