- Normal Development
- Thelarche is the onset of secondary breast development between 8-13 years
- Breast development occurs during fetal development
- Menarche typically follows about two years after thelarche
- Complete breast development takes 2-4 years, up to age 18
- Hormonal Factors
- Estrogen causes breast adipose tissue growth
- Progesterone develops mammary glands and areolae
- Hormonal changes cause breast development to be asymmetrical
- Trends and Variations
- Age of thelarche has decreased 0.24 years per decade since 1973
- African American females average 8.9-9.5 years, Caucasians 10-10.4 years
- Premature thelarche occurs before age 8 without pubertal changes
- 14-18% of premature thelarche cases also have precocious puberty
- Premature Thelarche Characteristics
- Usually occurs between 0-2 years of age
- Breast development begins as firm disc-like area under areola
- Usually resolves within 6 months to 6 years
- No treatment required unless accompanied by other symptoms