The phenomenon of sore thighs in the seventh month of pregnancy is usually due to the growth of the fetus in the process of development, the uterus will increase the pressure on the inferior vena cava, resulting in the obstruction of blood circulation in the inferior vena cava, the blood flow is not smooth, the phenomenon of sore thighs will occur, this situation can be relieved by massage or hot compresses. Some pregnant women may suffer from calcium deficiency due to insufficient calcium intake during pregnancy, which may also cause osteoporosis and lead to thigh pain. Excessive exertion, due to prolonged sitting or standing will lead to poor blood circulation, which will also cause the occurrence of thigh pain. Usually should pay attention to keep warm, pay attention to rest, appropriate amount of calcium supplements to reduce the symptoms.