Lower back pain after giving birth can be caused by ligament laxity, post-partum exertion or reflex pain. 1. Ligament laxity: In order to deliver the fetus, the ligaments connecting the pelvis during pregnancy will become relatively loose. As the gestational age gradually increases, the ligaments become lax, resulting in low back pain. Because it takes time for the ligaments to repair after childbirth, low back pain may also accompany the birth of a child. 2. Postpartum exertion: After giving birth to a baby, a pregnant woman cannot get enough rest, and the symptom of low back pain will occur. During pregnancy, the lumbar region itself is under a lot of pressure, which can cause some damage to the lumbar spine. When the lumbar spine suddenly loses pressure after giving birth to a child, coupled with insufficient sleep time for breastfeeding babies, the phenomenon of lumbar pain will occur. 3. Reflex pain: low back pain after giving birth to a child may be a kind of reflex pain, and postpartum uterine contraction recovery related to many pregnant women will be accompanied by this symptom, is a common phenomenon. After giving birth to a child with significant back pain, it is recommended to consult a doctor in time, to follow the doctor’s instructions for treatment.