Premature Breast Enlargement (Premature Thelarche)

Normal Puberty

Puberty is the maturation stage a person goes through when they develop secondary sexual characteristics. Usually, puberty occurs between the ages of 8 and 12 years in girls and between 9 and 14 years in boys.

Among girls, the signs of puberty are usually breast enlargement and hair growth in the pubic region and armpits, followed by menstruation. Among boys, the signs are usually enlargement of the penis and testicles, hair growth in the pubic region and armpits, muscle growth, facial hair growth, and deepening of the voice.

Both girls and boys may get acne and both usually experience a growth spurt over a period of two or three years where they reach a height that is closer to their adult height.

Premature Breast Enlargement (premature thelarche)

Premature breast enlargement, or premature thelarche, is the enlargement of breasts in girls at an abnormally early age, usually somewhere between birth and six years of age.

Premature thelarche is generally a harmless and temporary condition and breast enlargement is usually the only sign of abnormality. The breasts can stay enlarged for several years. However, they eventually decrease in size before the girl begins puberty.


Usually, no cause of premature thelarche can be identified, although it can arise as a response to exposure to certain drugs or exposure to estrogen, when a child consumes a mother’s contraceptive pill, for example. Some experts believe that girls who have premature thelarche simply experience a temporary period of being more sensitive to normal estrogen levels.


One or both of the child’s breasts start to increase in size or they may go up and down in size. There are no other signs of puberty such as the growth of pubic hair or rapid body growth. The breasts eventually stop enlarging and decrease in size, although it can take several years for the breasts to return to normal.


Girls who have premature thelarche do not usually experience any complications. The condition usually resolves independently and girls go on to experience puberty as normal. In some cases, it is the first sign of precocious puberty, but this is not common. Precocious puberty refers to the early onset of puberty, usually before 8 years of age in girls.

Precocious puberty is more likely in cases where the breast enlargement has occurred after the age of 2 or 3 years and when other signs of puberty are present such as the growth of pubic hair or an enlarged clitoris. In these cases, treatment may be required to interrupt the maturation process.


A doctor examines the child to check for any other signs of puberty. This does not usually require clinical tests, but these tests may be performed if the doctor suspects that any abnormalities maybe causing the enlargement. In those cases, hormone profiling, bone growth assessment, and ultrasound of the womb and ovaries may be carried out. If a doctor suspects the premature thelarche is a sign of precocious puberty, the patient may be referred to an endocrinologist, a specialist in hormone disorders who will advise about treatment options for halting the maturation process, if required.

Further Reading

Last Updated: Feb 27, 2019

Sally Robertson

Written by

Sally Robertson

Sally first developed an interest in medical communications when she took on the role of Journal Development Editor for BioMed Central (BMC), after having graduated with a degree in biomedical science from Greenwich University.


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