Large postpartum buttocks may be caused by fat deposition, widening of the pelvis, bad habits and other reasons. 1. Fat deposition: it may be that women supplement too much nutrition during pregnancy and breastfeeding, and the excess nutrition will be easily deposited in the arms, resulting in a big butt after delivery. 2. Widening of the pelvis: during vaginal delivery, when the fetus passes through the bone birth canal, it will make the gap between the bone joints wider, that is, the pelvis will become wider, which will result in a big butt after delivery. 3. Unhealthy habits: During pregnancy and after delivery, women sit or lie down for a long time, and when the muscles are relaxed, it is easy to cause the arm to become loose and big, so the buttocks will be big after delivery. Postpartum women with big buttocks should avoid sitting and lying down for a long time in their normal life, and they can improve it through proper exercise.