Low back pain after normal delivery may be caused by hormone imbalance, uterine posterior position or lumbar muscle strain, etc. The details are as follows: 1. Hormone imbalance: it means that the hormone level in the body has not recovered completely after a normal delivery, so it will cause the pelvic ligaments and lumbar ligaments to be more loose, which will cause back pain, no need to worry about it, and it will usually be relieved after some time. 2. Posterior uterine position: After giving birth, the uterus will be tilted backward, which will be accompanied by symptoms such as lumbar pain or abdominal distension, thus causing back pain after giving birth, you can improve the position of the uterus by lying down. 3. Lumbar muscle strain: may be due to the smooth labor will make the pregnant woman lumbar back muscles continued to force, there will be lumbar muscle damage, and then manifested in the postpartum lumbar pain, accompanied by swelling or numbness and other symptoms, can be through the massage or massage and other ways to relieve. It is recommended that mothers should pay attention to keep warm, pay attention to rest, and avoid overwork. If the symptoms of postnatal back pain persist, you should go to the hospital to find out the cause of the problem and then give symptomatic treatment.