It is the Tanner 2 stage of breast development (a scale used to analyze changes in people from childhood to adulthood). The first stage is the non-developed prepubescent state of breasts. Thelarche is usually the first sign of puberty. It usually occurs after age 8, and is the first evidence of puberty in 60% of women. It usually ends at age 13. However, it can sometimes happen earlier. When this happens, it can be by itself (called isolated premature thelarche). It could also be a wider pattern of precocious puberty (sexual development happening too early). 