Research dealing with exercise during pregnancy continues to demonstrate marked benefits for mother and fetus. The type, intensity, frequency, and duration of the exercise seem to be important determinants of its beneficial effects. Maternal benefits include improved cardiovascular function, limited weight gain and fat retention, improved attitude and mental state, easier and less complicated labor, quick recovery, and improved fitness. Fetal benefits may include decreased growth of the fat organ, improved stress tolerance, and advanced neurobehavioral maturation. Currently, the offspring are leaner at 5 years of age and have a slightly better neurodevelopmental outcome. Postpubertal effects are still unknown. In the absence of medical contraindications, women should be encouraged to maintain their prepregnancy activity level.