The length of male newborns is usually 48.7~52.1cm; the length of female newborns is usually 48~51.4cm. Length is the vertical distance from the top of the head to the soles of the feet, and newborns are usually measured in the supine position on a measuring bed. The length of male children is about 50cm at birth, 61~63cm at 3 months of age, 75cm at 1 year of age, and 86~87cm at 2 years of age. After 2 years of age, the growth rate of height tends to stabilize until puberty, and puberty ushers in the second peak of growth and development. The length of girls before the age of 2 is roughly the same as that of boys. Length is affected by endocrine and genetic factors, and there are individual differences. Therefore, height should be assessed on a continuous basis, taking into account individual differences to make a correct judgment.