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.