Gestational diabetes mellitus (GDM), which is maternal hyperglycemia that arises primarily during the third trimester of pregnancy, is usually diagnosed at 24 to 28 weeks of gestation with an oral glucose challenge.
Women who have risk factors for gestational diabetes, however, may have this test earlier in the pregnancy. Using new diagnostic criteria, it is estimated that gestational diabetes affects 18% of pregnancies1.
Physical activity performed during pregnancy benefits a woman’s overall health. Instead of detraining, pregnant women undertaking moderate-intensity physical activity can maintain or increase their cardiorespiratory fitness2. Furthermore, maternal exercise during pregnancy does not increase the risk of low birth weight, preterm delivery, or early pregnancy loss. On the contrary, regular exercise participation likely reduces the risk of pregnancy complications, such as preeclampsia and GDM, and shortens the duration of active labor3,4.
Physical activity during pregnancy may prevent both GDM and possibly later-onset T2D, and engaging in regular physical activity before pregnancy frequently has been associated with a reduced risk of developing GDM. In a recent clinical trial, a moderate physical activity program performed thrice weekly during pregnancy was found to improve levels of maternal glucose tolerance in healthy, pregnant women5 and higher levels of physical activity participation before pregnancy or in early pregnancy significantly lower the risk of developing GDM6.
Similarly a recent meta-analysis reported that pregnant women with GDM who exercised on a cycle or arm ergometer or performed resistance training three times a week for 20–45 min experienced better glycemic control, lower fasting and postprandial glucose levels, and improved cardiorespiratory fitness2. The same number of exercising women was prescribed insulin to control their blood sugars compared with sedentary women, however, and pregnancy outcomes were unchanged.
Compared with less vigorous activities, exercise intensity that reaches at least 60% of heart rate reserve (HRR) during pregnancy while gradually increasing physical activity energy expenditure reduces the risk of developing GDM7. The more vigorous the exercise, the less total exercise time is required. Thus, the general consensus is that higher levels of moderate physical activity (aerobic or resistance training) may reduce the risk of developing GDM during pregnancy and lower blood glucose levels in women who do develop it. Prevention of glucose tolerance during pregnancy may be possible, however, if women of reproductive age engage in leisure time physical activity in advance of becoming pregnant8.
In summary, women at high risk for GDM may be able to prevent it with lifestyle management during pregnancy. In those who develop GDM, dietary improvements and regular physical activity are frequently sufficient to manage hyperglycemia, although insulin and oral medications may be used when these changes are not enough. Management of blood glucose levels ensures better pregnancy outcomes and improves the health of both the mother and the fetus. Engaging in 30 min of moderate intensity physical activity on most, if not all, days of the week has been adopted as a recommendation for all pregnant women.
Recommended Exercise Prescription for Women with Gestational Diabetes |
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Mode
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Aerobic: Walk, stationary cycle, swim, aquatic activities, conditioning machines, prenatal exercise classes, prenatal yoga, seated exercises, and possibly jogging or running (if highly active before pregnancy) Resistance: Light or moderate resistance exercises
Exercises to Avoid: Activities lying flat on the back and any that increase the risk of falling or abdominal trauma (e.g., contact or collision sports, horseback riding, downhill skiing, water skiing, soccer, outdoor cycling, basketball, most racquet sports, and scuba diving) |
Intensity
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If inactive: moderate-intensity aerobic activity (40–59% heart rate reserve, HRR, or “somewhat hard”) during pregnancy and postpartum If already active or doing vigorous activity: moderate- to vigorous-intensity activity (40–89% HRR, or “somewhat hard” to “hard”) |
Frequency
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3–7 days, spread throughout the week
Better done on most, if not all, days of the week |
Duration
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30 min/session (range of 20–45 min)
At least 150 min of moderate-intensity physical activity spread throughout the week |
Progression
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If just starting, increase duration of moderate exercise slowly; if already more active, maintain or lower intensity during pregnancy rather than attempting to progress to higher levels |
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In addition, anyone wishing to earn free CME credits through the ADA for completing a new self-assessment program on exercise and diabetes may do so now through the ADA’s web site at http://professional.diabetes.org/ce.