Exercise during pregnancy is safe and provides benefits to both mother and fetus. Assuming no pregnancy complications, women who are engaged in a regular exercise program can usually continue their program throughout pregnancy. Exercise can be started during early pregnancy in women who do not regularly exercise. Exercise during pregnancy can improve the chances of having a healthy baby.

Guidelines published by The American College of Obstetricians and Gynecologists encourage regular exercise during pregnancy. They emphasize that even mild to moderate exercise can have health benefits. Regular, consistent exercise, a 30-minute session 3 or more times a week, is ideal. Because of the changes in the maternal cardiovascular system some modifications in an exercise regime may be needed. Pregnant women should be aware that there might be a decreased amount of oxygen available for aerobic exercise during pregnancy. The duration and intensity of the exercise regimen should be tailored to maternal symptoms. Pregnant women should not exercise to the point of exhaustion. They should end their session when they become too tired or short of breath. Prolonged, motionless standing should be avoided during pregnancy, as should exercising while flat on the back. Both these activities decrease the amount of blood, and thus nutrients, going to the fetus.

Pregnant women who exercised prior to pregnancy can exercise more than those who were previously sedentary. Studies have shown that moderate exercise in fit women for up to 60 minutes at a time 5 days a week has no deleterious effects on pregnancy outcomes. Babies born to women who exercise during pregnancy may be leaner at birth, are more alert and more easily quieted. Recent studies have shown that sedentary women who start an exercise program in the first 8 weeks of pregnancy have improved placental growth, improved placental function and babies that are heavier, but not fatter, than non-exercising women. It should be noted that the increased weight was in lean body mass, not fat. Although more studies are needed this may be a useful therapeutic tool in women who are at risk for low-birth weight babies.

Exercise and diet have important effects on fetal growth. Exercise stimulates the growth of the placenta and decreases the incidence of fetal distress both before and during labor. Women who exercise strenuously during pregnancy have babies that are on average smaller than non-exercisers but the decreased weight is in body fat only. Of note these children tend to be leaner throughout early childhood and have higher scores on tests of language and intelligence. Pregnancy requires about an extra 300 calories a day; women who exercise regularly may have a greater caloric need. The type of carbohydrates in the diet may significantly affect fetal growth. Women who have a diet higher in processed carbohydrates (packaged breads, cereals desserts etc) and root vegetables (e.g. potatoes) will gain more weight and have heavier babies than women who obtain their carbohydrates from unprocessed sources such as whole grain breads, non-root vegetables, fruits and nuts.

Mothers benefit as much as their offspring from a regular exercise program. Exercise improves overall fitness and sense of well-being but also decreases the incidence and magnitude of the aches and pains experienced by many pregnant women. Mothers who exercise regularly during pregnancy tend to have less fat deposition and are more likely to have a shorter and less complicated birth. Postpartum recovery is quicker in women who exercise.

Pregnant women have a constantly changing center of gravity as pregnancy progresses and thus need to be careful about exercise that requires a lot of balancing. Care should be taken to avoid falls and subsequent abdominal trauma. As I tell my patients, make sure to hold on when using the treadmill! Pregnant women also need to drink plenty of fluids to avoid dehydration. They should not become overheated during exercise; attention to appropriate clothing and the exercise environment will prevent overheating.

Complications of pregnancy may not allow all pregnant women to engage in an exercise program. However the vast majority of women and their children will benefit from regular exercise. It is important to discuss an exercise program with your obstetrician.