Height growth is a continuous, stage-by-stage process. Throughout the growth and development process, height growth does not occur at equal speed and shows different characteristics at different stages.
At present, the average length of newborn babies in urban China is 50cm, and male babies are longer than female babies. After birth and before the age of three, children are in the first rapid growth period. During this period, the fastest growth in height is within three months of age after birth. Thereafter, the overall rate of height growth is also faster until three weeks of age.
After three weeks and until puberty, there is a period of steady growth of about 5 to 7 cm per year.
Puberty begins when girls are 10 to 12 years old and boys are about 13 years old. This is the second rapid period of height growth in adolescents until the end of puberty at 18 to 20 years of age. Thereafter, the rate of height growth gradually slows down.
As they grow older, boys reach their maximum height around age 24 and girls around age 22.