Puberty is that episode in development when a child develops into an adolescent with the physical ability to reproduce. For girls these changes include:-

Breast development. The first sign of breast development (the 'thelarche') is enlargement of the nipples around the age of 11years (normal range 9-14). Full breast development takes about four years but may last as long as nine years. Frequently, one breast may seem to enlarge faster than the other although generally nature will ensure that they are equal when fully developed.

Pubic hairs start to show around the time of breast development and the axillary (armpit) hair follows about two years after the pubic hair.

The various parts of the vulva (Figure 2.2) and the vagina slowly enlarge during puberty.