There are two causes of buttock pain in pregnancy: 1. calcium deficiency; 2. as the fetus grows up, it compresses the sciatic nerve of the pregnant woman. The demand for calcium becomes bigger during pregnancy, if not supplemented in time, leg pain and buttock pain will occur, so you can start to supplement calcium from the 16th week of pregnancy. Usually, you can also drink more bone broth and milk, and eat more tofu, seaweed and other calcium-containing foods. You should also pay attention to more sunshine to promote the absorption of calcium. The enlargement of the fetus and the edema during pregnancy will have some pressure on the sciatic nerve, causing contracture of the hip muscles and pain in the buttocks. The pressure on the sciatic nerve can be relieved by appropriate exercise, such as moderate swimming, during normal times. Don’t always sit in one position, you can put your buttocks slightly higher when you sleep.