Puberty

Puberty refers to the years of rapid physical growth and sexual maturation that end childhood, producing a person of adult size, shape, and sexuality. The forces of puberty are unleashed by a cascade of hormones that produce external growth and internal changes, including heightened emotions and sexual desires.

The process of puberty normally starts sometime between ages 8 and 14. Most physical growth and maturation ends about four years after the first signs appear, although some individuals (especially boys) add height, weight, and muscle until age 20 or so. Over the past decades the age of puberty has decreased, perhaps for both sexes, although the evidence is more solid for girls (Biro et al., 2013; Herman-Giddens, 2013).

For girls, the observable changes of puberty usually begin with nipple growth. Soon a few pubic hairs are visible, followed by a peak growth spurt, widening of the hips, the first menstrual period (menarche), a full pubic-hair pattern, and breast maturation (Susman et al., 2010). The average age of menarche among normal-weight girls is about 12 years, 4 months (Biro et al., 2013) although variation in timing is quite normal.

For boys, the usual sequence is growth of the testes, initial pubic-hair growth, growth of the penis, first ejaculation of seminal fluid (spermarche), appearance of facial hair, a peak growth spurt, deepening of the voice, and final pubic-hair growth (Biro et al., 2001; Herman-Giddens et al., 2012; Susman et al., 2010). The typical age of spermarche is just under 13 years, almost a year later than menarche. Averages as well as age vary markedly, as soon discussed: The averages above are for well-nourished adolescents in the United States