A little bulge on one side of a 9 1/2 week old girl’s breast may be a sign that the child is about to enter the puberty stage of development. But it can also be caused by breast disease. The start and end of pubertal development in girls is about 9 to 12 years old, the first development is the breasts, breasts start to develop, you will find that the breasts are a little bulging, with the passage of time, the development of the breasts will be more obvious, such as nipple protrusion, areola enlarged, mammary glands development, breast enlargement, and so on. And with the development of genitals, pubic hair will appear on the vulva, and there will be the first menstruation and so on. However, it can not be completely judged to be 9 and a half year old children, into the puberty development stage caused by, but also may be breast cancer, breast fibroids and other mammary gland disease triggered. Adults need to observe the situation of the girl’s breasts, if there is no abnormality, then generally do not need to take treatment measures, but if there is an abnormality, but also need to go to the hospital for relevant examinations, for the cause of the treatment.