The interaction between metabolic syndrome and physical activity, and risk for gestational diabetes mellitus.

AIMS Metabolic syndrome (MetS) is a cluster of risk factors which increases risk of cardiometabolic diseases in the adult population and increases risk for pregnancy complications such as gestational diabetes mellitus (GDM). Epidemiological data indicate that moderate-to-high levels of physical activity reduces the risk for GDM. The study aims to determine whether the association between MetS and GDM is affected by physical activity. METHODS We performed a prospective cohort study among 1373 pregnant nulliparous women in Adelaide, South Australia. At 9-16 weeks' gestation, demographic, lifestyle and self-reported frequencies of physical activity were obtained, and a non-fasting blood sample was taken for assessment of MetS, defined using the International Diabetes Federation criteria. GDM was diagnosed at 24-28 weeks' gestation using the World Health Organization classification. RESULTS 1158 pregnant women were included: 107 (9%) women had MetS in early pregnancy, and 184 (16%) developed GDM. Having MetS increased the risk of developing GDM (37.4% vs. 13.7%, adjusted RR 2.5; 95% CI 1.7, 3.6). The interaction effect (RR; (95% CI) between MetS and physical activity was not significant (vigorous physical activity: 2.60; 0.46, 14.71) for ≥ 4 times per week; less vigorous activity; 0.77; 0.15, 4.02 for ≥ 4 times per week; stair climbing ≥ once day (1.16; 0.54, 2.51), all compared to no physical activity). CONCLUSIONS Physical activity was not an effect modifier in the association between GDM and MetS. Information collected about the nature and extent of physical activity needs to be more detailed and granular to determine whether physical activity really has an effect.