Postpartum back pain may be caused by physiological factors such as laxity of spinal ligaments, overweight of the fetus at the end of pregnancy, or it may be caused by muscle strain, myofasciitis, and other reasons. 1. Physiological factors: the fetus entering the pelvis during pregnancy may lead to spinal ligament laxity, and the rapid weight gain of the fetus in the second trimester of pregnancy will lead to the waist and back to be stretched, which will cause post-partum back pain. 2. Muscle strain: muscle strain is caused by direct or indirect injury to the muscles, and the patient will show muscle pain, local activity disorder, muscle stiffness regardless, muscle spasm and so on. Therefore, postpartum back muscle strain, there will be back pain performance. 3. Myofasciitis: Myofasciitis may be caused by acute or chronic strain of muscles and fascia, and long-term improper posture and fatigue may induce the disease. Patients will experience localized muscle pain, tenderness, muscle tension, and restricted movement. If myofasciitis occurs in the postpartum back, the symptoms of back pain will appear. 4. Other: maternal postpartum back pain may also be caused by lumbar disc herniation, lumbar muscle strain and other factors. If the back pain is caused by physiological factors, the symptoms will usually be relieved after a period of rest. If the back pain is caused by disease, you need to consult a doctor in time and follow the doctor’s instructions.