Late development of height, that is, when normal children enter puberty, there is no growth acceleration, but after other children of the same age stop growing or growth slowdown, only gradually began to grow faster, that is, to reach the right time height will still grow, medically known as “physical growth retardation”, commonly known as ” late growth”. There is a certain genetic background for late growth, which can be judged by observing the speed of height development, bone age test and trace element test. 1, according to the speed of height development (1) infancy: that is, from birth to 3 years old, this stage is the fastest growth, the first year after birth can grow 25cm, 1-3 years old average annual growth of about 10-12cm, to 1 year old height of about 75-78cm, 2 years old about 87-89cm, 3 years old about 97-99cm; (2) childhood: that is, from the age of 3 years old to before puberty, this period of growth is mainly regulated by growth hormone, the growth of the growth hormone. During this period, growth is mainly regulated by growth hormone, and the growth rate decreases gradually, with an annual growth of 5-7cm; (3) puberty: the height of boys can grow 25-28cm throughout puberty, and the height of girls can increase by about 20cm. If the child’s height development is less than 70% of the above values, or if the child’s height is significantly lower than the average level of children of the same age, the child’s height is considered to be late. 2. Judgment based on bone age test Bone age is the abbreviation of skeletal age, which is determined with the help of specific images of bones in the X-ray camera. Clinically, the difference between bone age and life age is less than 3 years old, which is called developmental lag. 3. Judgment according to trace elements test When the child’s nutrition cannot meet the bone growth needs, it will lead to late development of height. So when there is a lack of calcium, phosphorus, zinc and magnesium, it will affect the height development, and the trace element test can be clarified.