Back pain after giving birth to a child may be calcium deficiency, muscle ligament relaxation caused by. 1. Calcium deficiency: the female body will consume a lot of calcium during pregnancy and childbirth, coupled with breastfeeding the baby after delivery, making the body calcium loss aggravated, resulting in a calcium deficiency in the post-partum state, coupled with the weight of the pregnant mother after giving birth to a child has not yet recovered and other easy to cause back pain. 2. Muscle ligament laxity: pelvic muscles and ligaments in women after childbirth for a period of time, will be in a state of relaxation, if the postpartum long time walking, sitting, resulting in the use of lumbar muscles, ligament strain, will also cause back pain. There are many reasons for back pain after giving birth to a child, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment.