Pain within the thighs in late pregnancy may be caused by fetal prenatal compression, exertion and separation of the pubic symphysis. 1. Fetal prelude compression: with the increase of pregnancy weeks and fetal growth, the pelvic floor tissues and pelvic compression will become more and more obvious, especially when the fetal prelude into the pelvis in late pregnancy, it can cause pain in both sides of the thighs, which is a normal physiological phenomenon. 2. Exertion: when pregnant women walk for a long time or stand for a long time, it will also cause pain in the inner thighs, which can be relieved after sufficient rest. 3. Separation of pubic symphysis: After pregnancy, the hormone level of pregnant women rises, especially the relaxin secreted by the placenta, which will make the pelvic ligaments loose, some pregnant women will also relax and separate the pubic symphysis, which will cause obvious pain and activity limitation, and the pain can be radiated to the root of the thigh, and it will be recovered gradually after delivery. Therefore, the clinical late pregnancy thigh pain on both sides of the thigh can go to the hospital, and under the guidance of the physician to give the appropriate treatment.