Back pain after giving birth to a child may be caused by calcium deficiency, increased burden on the lower back and uterine contraction. 1. Calcium deficiency: Calcium deficiency may lead to osteoporosis, if coupled with prolonged weight bearing and incorrect posture, the phenomenon of back pain after giving birth to a child will occur. 2. Increased burden on the waist: prolonged breastfeeding or prolonged activities will lead to increased burden on the waist, which in turn will lead to the phenomenon of back pain after giving birth to a child. 3. Uterine contractions: the back pain that occurs after giving birth to a baby is generally contraction pain, which is aggravated by breastfeeding, and is a normal phenomenon. Pregnant women must get enough rest after giving birth to a child, if the rest state of the back pain can not be relieved, it is recommended to go to the hospital in a timely manner, under the guidance of the doctor to deal with.