The phenomenon of lower back pain at 36 weeks of pregnancy is divided into physiological and pathological. The physiological condition is that the fetus is growing and the uterus is enlarging, so the belly is bulging forward more obviously, which will change the center of gravity and cause the lumbar pain due to the gravity on the lumbar spine. When this symptom occurs, you should try to pay attention to rest and not overexert yourself. If the pain is obvious, you can take the massage to relieve the pain, gently massage the waist can promote blood circulation and improve lumbar pain. If in the middle and late stages of pregnancy, insufficient calcium supplementation for pregnant women will lead to symptoms of calcium deficiency, showing lumbar pain, which requires timely calcium supplementation. There is also a case of lumbar disc herniation or lumbar spine hyperplasia due to a change in the center of gravity, which can cause severe lumbar pain and requires prompt medical attention.