DISCUSSION
We were unable to show that a voluntary, lightweight, once-weekly exercise program improves glycaemic control sufficiently to prevent or delay insulin prescription in women with GDM.
Exercise before, during and after pregnancy has important health benefits for the mother, including cardiovascular function, prevention of preeclampsia, gestational diabetes, varicose veins, deep vein thrombosis, lower back pain, and better mood and psychological wellbeing15. Regular exercise also limits weight gain during pregnancy and fat retention after delivery 16. There further is decreased risk of preterm delivery, labour is shorter and there are less perinatal complications 15. The off-spring from physically active mothers have lower birth weight, lower fetal body fat, and do well during their early life years17. Women who were physically active prior to pregnancy are at lower risk of GDM, and engaging into regular exercise early in pregnancy can prevent GDM 18.
Some studies implemented 3 exercise sessions per week and reported some clinically relevant effects 9. In our setting, women consulting for the follow-up of the GDM are limited by time and travel constraints to attend at more than a weekly session. Thus, we evaluated if a lightweight intervention, combined with the advice to accumulate at least 5000 steps a day would be enough for a clinically relevant effect. The absence of a benefit may be due to the low volume of exercise sessions.
Although some centers use oral drugs to treat GDM, the current approach in our center is the use of insulin. Insulin does not cross the placenta and is therefore the safest medication used to treat diabetes in pregnancy, but is associated with some risks, as hypoglycemia, is costly, requires specific teaching by specialized nurses and women are reluctant to perform the injections. Therefore, if women with GDM could avoid the use of insulin, not only by a strict dietary management, but also by physical activity, as suggested by previous studies, this could ease and reduce the costs of GDM management. In our setting, insulin was generally prescribed only a few weeks after starting the exercise program, which limited the potential benefit.
The limitations of our study may explain the apparent absence of benefit. We had to stop the recruitment before completing the calculated sample size. The exercise program was light and of short duration, and some women attended infrequently the sessions.