When the “Sheng Yuan milk powder suspected of causing precocious puberty” incident was in full swing, on August 15, 2010, the Ministry of Health informed that the children in Hubei could only be diagnosed as simple precocious breast development rather than true precocious puberty. What is simple premature breast development? What is precocious puberty? Some members of the public still feel half-informed about these professional issues. Precocious puberty refers to the appearance of secondary sexual characteristics that do not correspond to age before the age of 8 for girls and 9 for boys. For example, periodic vaginal bleeding, breast enlargement, pubic hair and axillary hair growth, etc., accompanied by physical development, such as height, weight and bone growth, can be called precocious puberty. According to the different pathogenesis, precocious puberty in children is clinically classified into true (central) precocious puberty and pseudo (peripheral) precocious puberty. True precocious puberty is identical to true puberty and can produce germ cells and have the ability to have children; pseudoprecocious puberty only has the development of secondary sexual characteristics caused by the action of sex hormones, but cannot produce sperm or eggs, so it does not have the ability to have children. The causes of true precocious puberty are complex, and can be caused by organic diseases such as intracranial infection, trauma or tumor that trigger the “switch” of puberty development, or the so-called idiopathic true precocious puberty for which no cause can be found; in addition, children who “take too many supplements” In addition, children who “take too many supplements”, children who love to eat foreign fast food, children who often watch romantic dramas, and children who sleep with the lights on, may develop early. The sex hormones that cause pseudo-precocious puberty can come from inside or outside the body. In vivo can come from various tumors that secrete sex hormones, and in vitro can come from food or drugs. In addition to prolactin, estrogen, progesterone, growth hormone, thyroid hormone, adrenocorticotropic hormone, insulin and other hormones are also involved in the regulation of milk secretion in dairy cows in order to complete the process of lactation. The hormone content in milk is affected by the mother’s breed, different physiological stages, the number of conceptions and the nutrition of the feed. Generally speaking, the range of estrogen and progesterone content in both raw milk and commercially available milk varies widely, and China prohibits the detection of artificial chemically synthesized sex hormones in milk powder. Simple premature breast development refers to the advancement of breast development in girls, without the appearance of other sexual characteristics such as pubic hair and axillary hair, and without the advancement of bone age and growth acceleration, mostly occurring in infants and children from 6 months to 2 years old, often due to “micro puberty”. The incidence is about 2 per 1,000. Micro puberty” is a physiological phenomenon early in life, during this period, some babies’ hypothalamus-pituitary-gonadal axis is in a temporary “activation state”, “negative feedback regulation” has not yet. “Negative feedback regulation” is not yet sound, slightly by external stimulation, such as mood abnormalities, there will be a specific sex hormone fluctuations, but the hypothalamus-pituitary-gonadal axis will not respond to it, such as soon after birth, male infants may appear testicular mild enlargement, penile erection, this phenomenon can last until about half a year old. . Some female infants who are sensitive to estrogen may show more pronounced breast development, and very few may even show a little bleeding similar to menstruation in adolescent girls. This manifestation in infancy can be seen as a small preview of the real “big” adolescence a few years later, which is medically referred to as “micro-puberty”. According to data from the Ministry of Health, about two out of 1,000 babies will enter “micro-puberty” during this period and show symptoms of “precocious puberty”. It seems that “simple early breast development” is pseudo-precocious rather than “real precociousness”. Generally speaking, simple premature breast development will subside naturally (most children will heal themselves after the age of two) and will not have any adverse effects on the growth and development of children, so no treatment is needed. However, it is necessary to avoid stimulation by harmful factors and to intensify follow-up. Parents must be aware that some children who are initially diagnosed with simple precocious breast development may also have an underlying cause, and if this cause is not removed in a timely manner and persists for a long time, the breasts may not subside or continue to increase in size, and true precocious puberty may develop. If true precocious puberty occurs, it can affect the final height and mental health of the child. Therefore, regular follow-up examinations, review of bone age, uterine and ovarian ultrasound, and sex hormone and gonadotropin-releasing hormone tests if necessary should be emphasized to detect true precocious puberty and treat the underlying disease in a timely manner.