Exercise
The role of exercise in women with GDM has been controversial in the past because maternal exercise on a bicycle ergometer has been associated with fetal bradycardia. Subsequent small studies 40,41 have shown small transient increases in fetal heart rate after maternal exercise. There were no fetal complications in either study.
Durak et al.42 found that uterine activity, defined as contractions with an external tocometer deflection of > 15 mmHg above baseline for > 30 seconds, varied in response to different types of aerobic exercise, even at comparable levels of exertion. The bicycle ergometer, treadmill, and rowing ergometer led to uterine activity in 50, 40, and 10% of exercise sessions, respectively. The recumbent bicycle and upper body ergometer did not lead to any increase in uterine activity. Therefore, the authors concluded that the recumbent bicycle and upper body ergometer were the safest forms of aerobic exercise for pregnant women. In addition, they recommended teaching women to palpate their uterus during exercise to detect subclinical contractions and to discontinue the exercise if contractions occur.
A potential benefit of exercise in women with GDM is improved glycemic control. One small trial randomized women with GDM to diet and exercise with an arm ergometer versus diet alone for 6 weeks. Researchers found that the diet-and-exercise group had a significant decrease in glycated hemoglobin levels and in both fasting and 1-hour plasma glucose levels during a glucose challenge test compared to the diet-alone group.43 Another trial, in which women with GDM were randomized to a partially home-based exercise program, did not find any reduction in blood glucose level, although the women did have an improvement in cardiovascular fitness.40 Based on the potential benefits of exercise in women with GDM, the ADA recommends starting or continuing a program of moderate exercise in women without medical or obstetrical contraindications.2