Exercise, Pregnancy, and Preterm Birth

Obesity is a risk factor not only for preterm delivery, but also for medical complications during pregnancy. Consuming a well-balanced, appropriate-calorie diet combined with regular physical exercise is an effective way to control weight. During pregnancy, many women are concerned that maintaining regular physical activity is associated with preterm delivery, and they therefore give up exercise. This may lead to more rapid weight gain and higher risk for diabetes or hypertensive complications.

Aune and colleagues found that prepregnancy exercise is not associated with an increased risk for preterm delivery and that exercise during pregnancy is associated with a lower risk. In a dose/response analysis, they found that each extra 3 hours of exercise lowers the risk by 10%. Obviously, there are conditions in which exercise (especially vigorous) is not advised; these include bleeding, multifetal pregnancy, and immediate risk for preterm delivery owing to cervical shortening or rupture of membranes. However, most pregnant women can carry on exercising.

Women who exercise regularly may follow a healthier diet, be less likely to smoke, and be exposed to less stress overall. Women who are active before pregnancy may also differ from those who start to exercise during pregnancy. These differences could affect their overall risk for preterm delivery. And other confounding factors may be responsible for the observed differences. In RCTs, however, confounding factors should be equally present in all groups, and cohort studies tried to control for these factors.

The optimal duration and intensity of physical activity during pregnancy remains to be determined. Are different types of activity equally harmless, and do some activities carry risks? For now, on the basis of these findings, we can reassure pregnant women that by staying active, they do not compromise the outcome of their pregnancy.  I think that into the second and third trimester, its not a good idea to take up a new exercise routine as your body wont already be used to the stresses brought about by the exercise and may cause discomfort for your baby.   Common sense should always prevail.