Before the age of 8, young children may experience an increase in the size of one or both breasts, which may be accompanied by tenderness. This breast “development” phenomenon is not all precocious sexual maturity, most of them are just a special performance of the second sex characteristics, a developmental variation phenomenon, but also a self-limiting disease, called simple breast development in children, also known as pseudo precocious sexual maturity. The hormones of the human endocrine system are secreted in a complex and rigorous manner under normal circumstances, with the hypothalamus, pituitary gland and gonads forming a mutually constraining axis, and once this constraint is broken, hypersecretion of the gonads will produce precocious sexual development; conversely, sexual immaturity. The normal development of girls is from about 10 years old breast development, 12 or 13 years old began to menstruate, the best age of menarche is about 13 and a half years old; boys are generally two years later than girls development, 12 years old began to have pubic hair and scrotum development, at the age of 15 years old appeared the first ejaculation. The time difference in between is about two and a half years. However, if these symptoms appear before the age of 8-9 for girls and 9-11 for boys, it is called precocious puberty. Clinically, precocious puberty is divided into two categories, one is true precocious puberty and the other is pseudo precocious puberty. True precocious puberty means that the development process is the same as that of real puberty, not only showing the maturation of internal and external reproductive system, but also accompanied by the sudden increase of growth and the maturation of bone age. Pseudo-precocious puberty is only the development of the external reproductive system, without growth acceleration and maturation of bone age, also known as simple breast development in children. The characteristics of simple breast development in children are: although there is a slight increase in breast size, but the areola and nipple are normal, no other secondary sexual characteristics development phenomenon, and the diameter of the enlarged breast does not exceed 5cm, grasp these characteristics can be distinguished from true precocious puberty. The common causes of true and false precocious puberty are idiopathic precocious puberty, intracranial tumor, primary hypothyroidism, etc., while most children have pseudoprecocious puberty. Pseudoprecocious puberty is caused by gonadal tumors, adrenal hyperplasia or tumors that produce large amounts of sex hormones, or by the intake of drugs and foods containing sex hormones. Most of them can show one or more signs of sexual development alone. Hormones and hormone-like substances entering the body from food disrupt the physiological balance, which can be the direct cause of pseudoprecocious puberty. Environmental hormone-like pollutants, on the other hand, become an important contributing factor to its onset, which may be the main factor in the current marked increase in the onset of precocious puberty in children. In summary, there are several types of reasons: 1. With the improvement of living standards, children’s growth and development are accelerated, children and adolescents are generally taller than the previous generation, and there is an early trend of sexual development and sexual maturity. According to the normal pubertal development in the past, breasts start to develop at the age of 12 to 13, and the first menstruation mostly occurs at the age of 15 to 16, while the current generation of girls have breast development at the age of 10, and the first menstruation at the age of 12 to 13. 2, intake of food containing sex hormones or misuse of contraceptive pills. In recent years, a variety of health products and tonic products are listed first, many parents for children to increase nutrition, promote growth, as a health investment, often to the young children also long-term use. It has been confirmed that ginseng, royal jelly, pollen, chicken embryo, silkworm chrysalis, and height-enhancing elements are more sex hormones, and even gonadotropin-like substances. 3.Environmental pollution. In recent years, a large number of scholars at home and abroad have reported that a series of environmental hormone pollutants have been produced in nature due to the discharge of harmful substances and their decomposition substances into the environment from detergents, pesticides and plastic manufacturing plants. In addition, organochlorine pesticides are rarely used now, but they were released in large quantities in agricultural fields in the past, and their contents in soil, water and plants are still high. Studies have shown that both vegetables, fruits, and meat foods, influenced by environmental estrogenic substances, contain high doses of estrogen. The artificial feeding of hormones to poultry and livestock or ripening of fruits and vegetables is also a factor that cannot be ignored. All in all, excessive nutritional intake, indiscriminate consumption of some food or medicine to fill the marrow and kidney, as well as environmental pollution, food pollution, and visual pollution “not suitable for children”, are all causes of precocious puberty. The most serious problems that may arise from precocious puberty in children are early pregnancy and dwarfism. Due to the rapid growth of hormone levels, children with precocious puberty have a much earlier demand for the opposite sex than their peers, but their intelligence and sexuality are not yet mature, so they are prone to early love, early pregnancy and sexual crimes. Affected children may also have low self-esteem, fear and anxiety because they are physically different from their younger peers around them. Girls with premature menstruation are often very nervous, which affects their normal life and studies. In addition, early onset of sexual characteristics is often accompanied by accelerated skeletal growth, temporarily appearing to grow faster and taller than children of the same age, but because their bones fuse early, their final height is often shorter than normal. In conclusion, precocious puberty may cause harm to oneself, family and society, and is called a public health disorder. The prognosis is good, and no special treatment is needed. Most of them can subside on their own before puberty, but very few may continue to subside until after puberty, and very few may develop into true precocious puberty. Therefore, if a child is found to have breast development on one or both sides, it is important to first understand the child’s situation and determine whether it is simple breast development or true precocious puberty. If a child is found to have a tendency to precocious puberty, parents should promptly consult or consult a physician to find out the cause of the child’s precocious puberty and give corresponding treatment according to the different causes. At the same time, attention should be paid to help the child release psychological pressure and communicate more so as to cooperate with the treatment. In the diagnosis, we should not only look at the breast, but also look at other signs, such as an ultrasound of the abdomen to see if the child’s ovaries and uterus are developing, and also look at the development of the bones, because children grow faster after accelerated sexual development. The characteristic of estrogen’s effect on the human body is that it can cause the child to grow faster in the early stage, and inhibit the child’s growth in the later stage, and eventually the child will be shorter in height in adulthood. Next, the child should be given a cranial CT test to see if there is any tumor problem. If there is no tumor, it can be determined that it is true precocious puberty and treatment should be given. The main reason for premature breast development is that “the disease comes from the mouth”. In terms of daily diet, parents should control the food basket and avoid letting their children eat the necks of chickens, ducks, geese, animal sex organs such as cow whips and testicles. Don’t blindly give your child healthy foods like royal jelly and pollen, and there’s no need to let your child eat some supplements like ginseng and chicken essence. Out-of-season, unusually colored and shaped and expensive fruits and vegetables should also be avoided. The body will produce estrogenic substances after metabolizing high-fat foods, which will stimulate the development of the mammary glands, so children who consume too much high-fat foods will also induce premature development of the mammary glands. To prevent precocious puberty, we need to make sure that our diet is balanced, light, less oily and less sweet, and that we do not give our children visual pollution that is not suitable for children. Premature breast development in children is mostly transient, as long as the cause is ruled out in time, after reasonable treatment is generally good healing.