Eight months pregnant back pain is generally due to the following reasons: first, a long time of inactivity, pregnant women’s activities in the late pregnancy significantly reduce the activities can be caused by reduced lumbar muscle weakness and muscle strength, while the hormone secretion of pregnancy stage ligament is also flaccid, resulting in muscle weakness, further aggravate the pain and inflammation by the impact of the situation. Secondly, after the weight increase obviously, not only can cause lumbar muscle discomfort, but also because the activity and rest are obviously affected, it can cause bad posture, which can aggravate the pain of lumbar muscle, such as sleeping and rolling over, etc. It will increase the weight of lumbar muscle strength. Third, weight gain can significantly aggravate the previous lumbar spine disease, such as originally have lumbar disc herniation, arthritis, etc., will cause these conditions to aggravate. Fourthly, if pregnant women do not take enough calcium supplement, it can also cause calcium deficiency acidity and discomfort.