Pelvic pain after delivery is caused by pelvic instability and calcium deficiency. 1. Pelvic instability: during pregnancy, the uterus is bigger, the fetus and amniotic fluid will burden the pelvic cavity, then the sacroiliac joints and the pubic symphysis will have joint gaps, making the pelvic bone unstable, and the hormone level of the body is higher during pregnancy, so that the ligaments of the pelvic ring will become flaccid and soft, which will cause the pain of the sacroiliac joints after the birth. 2. Calcium deficiency: During pregnancy, the fetus needs more calcium, if not supplemented in time, it will lead to calcium deficiency and osteoporosis symptoms after delivery, causing local pain. 3. Pelvic floor muscle or ligament strain: the wrong force during labor can lead to pelvic floor muscle or ligament strain, causing pain. There may be other reasons for postpartum pelvic pain when lying down and rolling over, so it is recommended to go to the hospital in time to improve the examination and clarify the cause of the disease, and then give targeted treatment under the guidance of the doctor.