The biological age of the child is the age of life, which is the actual age after birth, while the biological age is the age at which the normal bone age should be after taking a film. If the biological age, i.e. the bone age, is small, it means that the growth and development of the child is slow and does not reach the life age. This is usually due to the hormonal problems in the body, especially when the growth hormone is low, which will affect the growth and development of the child, resulting in slow development. Of course, it may also be due to poor nutrition, other diseases, reduced exercise or lack of sleep and other factors affecting growth and development. Therefore, there are many reasons for low bone age, so it is important to find out the exact cause, whether it is due to a picky diet, inadequate food supply, diseases such as hypothyroidism or other reasons for slow growth. Therefore, it is important to find a doctor to clarify the situation and provide timely treatment to avoid serious consequences.