Breast development in 7 year old girls refers to precocious puberty, which is clinically defined as the development of breasts before the age of 8 years old, and is called precocious puberty. The child with precocious puberty needs to go to the hospital for a detailed examination to clarify the cause of the disease as well as to find out how precocious puberty is affecting the child, and to further treat the disease.7-year-old girls with breast development should go to the hospital to do a bone age test, as well as ultrasound tests of the uterus and the ovaries:1. Check the bone age to find out if there is any loss of height in the child at present, and whether the height at the age of the bone is in line with the actual height, as well as the extent of the loss. 2, Ultrasound of breast as well as uterus and ovaries to clarify the severity of precocious puberty at present, and to see whether the development of uterine follicles has reached the level of puberty at present. If there are abnormalities in bone age and uterus and ovaries, further blood hormone tests are needed for further correct and rational treatment.