The purpose of this study is to investigate how low intensity aerobic exercise effects BDNF and NGF gene expression exercise for pregnant women. 7 week old ICR mice, male(n=10), female(n=50), supplied by BIOKOREA were used in this study. After hyblidization, pregnant mice were categorized into 2 groups depending on exercise ; "non-exercise" group(n=20), "low-exercise" group(n=20). A series of genetic tests were performed to identify BDNF and NGF gene expression producing the following results, the statistical changes were noted for BDNF expression within brain tissue when comparing the following groups; the "non-exercise" group and "exercise" group(p<.05), Expression of BDNF among the group according to the low intensity aerobic exercise. The low intensity aerobic exercise group is much higher than non-exercise group(p<.05). Expression of NGF among the group according to the low intensity aerobic exercise. The low intensity aerobic exercise group is much higher than non-exercise group(p<.05). Therefore, it brings positive changes in growth and development of nerve cells as a protein that contributes to learning, memory and thinking skills and brain active role for the biological activities, including cell growth, which play an important role in BDNF and NGF compared with the non-exercise group rat pups bom in 30 minutes in the exercise group a statistically significant difference was found. If the point is increasing BDNF more effectively on brain active, low intensity aerobic exercise will have bigger impact onbrain active. Also, in terms of exercise prescription it is better to focus on quantity than intensity in order to grasp more on brain active fetus.