Based on age, the average height of a full-term child is 50 cm at birth, growing about 25 cm in the first year of life, 10 cm in the second year, and 5-7 cm in the third year of life. The height of a 3-week-old child is affected by endocrine factors, nutritional status, and genetic factors. 3-week-old children’s height can be affected by endocrine factors, such as lack of growth hormone or reduced sensitivity of the body to growth hormone, and may grow more slowly, resulting in short stature. In addition, if the child is chronically malnourished, it may also result in a short height compared to children of the same age. In addition, there are children whose height itself grows shorter due to genetic influence. 3-week-old children’s height will continue to change as they grow older, so parents should pay attention to regular testing of their children’s height. The parents should pay attention to regular testing of the child’s height. Avoid listening to some advertisements and interfering with the child’s height at will in order to have a higher height in the future, as long as the 3-week-old child’s height is within the normal range and normal parenting can be carried out. If you find that your child’s height is growing too fast or slow, you should go to the hospital to find out the cause and deal with it actively.