A major growth spurt occurs at the time of puberty. Around age 8 to 13 in girls and 10 to 15 in boys, kids enter puberty, which lasts from about two to five years. This growth spurt is associated with sexual development, which includes the appearance of pubic and underarm hair, the growth and development of sex organs, and in girls, the onset of menstruation.
Breast development is usually the first noticeable sign of puberty in girls.
About 15 percent of girls will develop pubic hair before breast development starts. The growth spurt begins. Pubic hair begins to appear, usually within 6 to 12 months after the start of breast development. Uterus and vagina, as well as labia and clitoris, increase in size. Pubic hair is well established and breasts grow further.