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Physical Activity Before and During Pregnancy and Risk of Gestational Diabetes Mellitus
A meta-analysis
DEIRDRE K. TOBIAS, SM1 CUILIN ZHANG, MD, PHD2 ROB M. VAN DAM, MD, PHD1,3 KATHERINE BOWERS, PHD2 FRANK B. HU, MD, PHD1,4 nancy (5,6). Children of women with GDM are more likely to be obese and have impaired glucose toleranceand diabetes in childhood and early adulthood (1). In a recent meta-analysis of randomized trials on the effect of treatment for GDM, various interventions for blood glucose control, including diet, glucose monitoring, insulin use, and pharmaceutical interventions, did not significantly reduce the risk for adverse perinatal and neonatal end points, including cesarean section and perinatal orneonatal death (7). Collectively, these data indicate that prevention of GDM altogether could be crucial for avoiding its associated adverse health outcomes. Physical activity has long been known for its role in improving glucose homeostasis through its direct or indirect impact on insulin sensitivity via several mechanisms. For instance, physical activity has independent effects on glucose disposal byincreasing both insulin-mediated and non– insulin-mediated glucose disposal (8,9). Physical activity can also exert long-term effects on improvement in insulin sensitivity through increased fatfree mass (10). Furthermore, the benefits of preventing or delaying the onset of type 2 diabetes among nonpregnant individuals have been reported repeatedly (11,12). Therefore, physical activity may have thepotential for preventing GDM and related adverse health outcomes. However, evidence for its impact on GDM has not been systematically synthesized. The aim of this systematic review and meta-analysis was to assemble the current evidence for the relationship between physical activity and the development of GDM. RESEARCH DESIGN AND METHODS Data collection Relevant published English-language articleswere identified by searching the Medline database (National Library of
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OBJECTIVE — Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy and is associated with a substantially elevated risk of adverse health outcomes for both mothers and offspring. Physical activity may contribute to the prevention of GDM and thus is crucial for dissecting the viciouscircle involving GDM, childhood obesity, and adulthood obesity, and diabetes. Therefore, we aimed to systematically review and synthesize the current evidence on the relation between physical activity and the development of GDM. RESEARCH DESIGN AND METHODS — Medline, EMBASE, and Cochrane Reviews were searched from inception to 31 March 2010. Studies assessing the relationship between physicalactivity and subsequent development of GDM were included. Characteristics including study design, country, GDM diagnostic criteria, ascertainment of physical activity, timing of exposure (prepregnancy or early pregnancy), adjusted relative risks, CIs, and statistical methods were extracted independently by two reviewers. RESULTS — Our search identified seven prepregnancy and five early pregnancy studies,including five prospective cohorts, two retrospective case-control studies, and two crosssectional study designs. Prepregnancy physical activity was assessed in 34,929 total participants, which included 2,813 cases of GDM, giving a pooled odds ratio (OR) of 0.45 (95% CI 0.28 – 0.75) when the highest versus lowest categories were compared. Exercise in early pregnancy was assessed in 4,401 totalparticipants, which included 361 cases of GDM, and was also significantly protective (0.76 [95% CI 0.70 – 0.83]). CONCLUSIONS — Higher levels of physical activity before pregnancy or in early pregnancy are associated with a significantly lower risk of developing GDM. Diabetes Care 34:223–229, 2011

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estational diabetes mellitus (GDM) is one of the most common complications of pregnancy, affecting...