Breasts smaller than before may be due to the following circumstances: 1, weight loss: because most of the breast is due to fat and mammary tissue inside the composition, weight loss when the fat content is gradually reduced, may make the breast fat content followed by a reduction in the breast, making the breast smaller; 2, breastfeeding: breastfeeding due to the secretion of milk to make the breasts swollen, after the cessation of breastfeeding, milk is no longer secretion of breasts is no longer filled, the breasts appeared to be small; 3, breast disease: such as breast hyperplasia, mammary fibroids, breast cancer, breast injuries, etc., it is best to go to the hospital to do a further checkup, if the pathology of the small size of the need to be treated aggressively.