I read an article in the news the other day about a woman who ran a full marathon, finished in the front half of the crowd, and then gave birth eight hours later. Though I've heard that exercising during pregnancy and walking around while in labor is healthy for pregnant women and can assist labor and delivery, this seemed like it was taking this concept to the extreme. Shouldn’t pregnant women be taking it easy in the days leading up to their baby's birth? Was it really a good idea for this woman to celebrate her baby’s birthday with a delightful 26.2-mile jaunt?

Extensive research has indicated that for mothers with good health and low-risk pregnancies, moderate exercise can offer a variety of obstetric and postpartum benefits. These benefits include reports of feeling better and more energetic during pregnancy, shorter and less difficult labor and delivery, and faster healing in the postpartum period. The concept of “moderate exercise,” however, is a relatively subjective one. What one pregnant woman feels is moderate exercise may seem quite extreme to another. What matters, according to studies, is that pregnant women do not overexert themselves or push their bodies beyond the limitations placed on it by their pregnancies.

A good rule of thumb according to most experts is that pregnant women should not engage in exercise more intense than what they would have done prior to becoming pregnant. Pregnancy is not the time to take up kickboxing, long-distance running or any other type of high-intensity exercise unfamiliar to them. This, however, is not the only way that pregnant women should control their exercise.

Studies have indicated the most dangerous aspect of aggressive exercise, beyond the potential for falling or impact, is the teratogenic effect of heat. This occurs as a result of increased body temperature due to metabolic rate increases during exercise combined with a similar effect created by pregnancy. Fetal temperature is consistently .9 to 1.8 degrees Fahrenheit above that of the mother, and when it is pushed to higher levels due to intense exercise the baby can suffer from congenital abnormalities, particularly related to the nervous system. Frequent overheating is also related to miscarriage or premature delivery.

Pregnant women should be under the careful supervision of their treatment professional when embarking on any form of exercise regimen. It is important for them to listen to their bodies and know when to step back in order to protect the health and safety of their babies.

Source: Wang, Thomas M.D. et al. Exercise During Pregnancy, American Academy of Family Physicians, April 15, 1998.