Sore back muscles after a normal delivery may be due to changes in hormone levels, post-partum exertion, muscle strain during pregnancy, etc., and need to be analyzed specifically. 1. Changes in hormone levels: A series of changes in hormone levels after delivery may lead to aseptic inflammation of the back muscles, resulting in soreness. 2. Postpartum exertion: After giving birth, the patient may be overworked, sleeping for a long time or keeping the same position for a long time, which may lead to back muscle pain. 3. Muscle strain during pregnancy: After pregnancy, as the fetus and the uterus grow, the back muscles may be affected by the prolonged pressure on the lower back muscles. The process of labor and delivery will also cause some tension on the back muscles, which will lead to back muscle pain after delivery. There are many other causes of postnatal back muscle pain, and it is recommended that patients who find themselves with postnatal back muscle pain that is not relieved for a long period of time should consult a doctor in time, and under the guidance of the doctor to complete the relevant examinations and treat the cause of the disease.