The main reasons for the increasing size of the breast, including the following aspects: 1, occupational lesions of the breast, and occupational lesions grow faster, patients need to immediately go to the hospital for ultrasound, basically can be a clear diagnosis, most of the cases of occupational lesions need to undergo surgical treatment. 2, due to the impact of pregnancy, is a normal physiological reaction of the body, the breasts in pregnancy is very Sensitive, mainly due to changes in hormone secretion levels after pregnancy, some patients not only have bigger and softer breasts, there may be overflow from the nipple.3. Breastfeeding, mainly due to the breasts of breastfeeding patients appear to have secretion function. Due to the large amount of milk secretion, the volume of the breast will be more than one times larger than before, which is a normal physiological function of the breast.4. Normal development of mammary glands, adolescents will show this state when their breasts are developing.