Growth and development is a continuous biological process. Growth refers to the growth of organ systems and overall body size; development refers to the perfection of tissue cell differentiation and functional maturation. Growth and development are dynamic changes in both quantity and quality of the organism. The two cannot be separated. Growth and development is an extremely complex process, basically regulated by genes, but gene expression can also be influenced by various factors inside and outside the body. The main factors affecting the normal growth and development of the organism are: 1) maternal nutrition, endocrine function and diseases are closely related to the growth and development of the embryo and fetus; 2) whether the daily diet and nutrient intake are appropriate; 3) a good family environment is the guarantee of normal growth and development, long-term emotional depression will lead to growth disorders; 4) the cells themselves cannot accept the regulation of hormones or growth factors and The value-added differentiation will also lead to abnormal growth and development, such as defective fibroblast growth factor-3 can cause cartilage underdevelopment, etc. Although the whole growth and development process is continuous, it is not smooth and uniform. Usually, human growth and development are divided into 4 stages, namely fetal stage, infancy, childhood and adolescent development. The growth and development characteristics of different growth stages I. Infancy (0-3 years old) From birth to the age of 1 year is the infant period, which is called the newborn period from the delivery of the fetus, ligation of the umbilical cord to 28 days after birth. According to the monitoring data in the 1990s, the average birth weight of normal newborns in China is 3.20-3.30kg, with male babies weighing 100g more than female babies, and the average length is 50cm. Infancy (and neonatal period) is the most rapid growth stage in a person’s life, with height increasing up to about 25 cm in the first year of life, 10-11 cm in the second year, and 4-7 cm per year thereafter. This growth phase is mainly regulated by growth hormone and nutrition. Second, the childhood period including preschool (3 ~ 6 or 7 years old) and school age (6 or 7 years old ~ 11 or 12 years old). The height growth rate of normal children starts to decrease year by year after the age of 4 years, and reaches its lowest point in prepubertal period, about 5~5.5 cm/year. Growth hormone and thyroid hormone are the main regulators of growth during childhood. Adolescence is the period from the beginning of the development of secondary sexual characteristics to full maturity, which is the stage of transition from childhood to adulthood. The age of onset of puberty depends on how early the hypothalamic-pituitary-gonadal axis is activated, usually starting at the age of 10-12 for girls and 12-14 for boys, two years later for girls. Puberty lasts on average about 6 to 7 years, with a second growth spurt, which can be obtained around 25 to 28 cm for boys and 25 cm for girls.