Breast development, or the growth of a girl’s breasts, is often the first sign of puberty for females.
It can be a time of excitement as well as anxiety, as girls get used to their changing body.
Patients can be seen by Texas Children's experts in Pediatric and Adolescent Gynecology.
Causes & Risk Factors
Breast development is caused by hormones released by the ovaries at puberty. These hormones cause fat to accumulate, causing your breasts to enlarge.
What happens during breast development?
The first sign of breast development is slight swelling under the nipple, a stage of development called breast buds.
As your breasts first start to grow, they can be very tender and sore. They may also itch as your skin gets stretched. Buying a first bra can help protect new breast growth and minimize pain. If the breasts grow rapidly, stretch marks may occur in the skin. These will fade over time.
The breasts will continue to grow as the girl’s body fat increases during puberty. They become rounder and fuller. The areola (the area around the nipple) may get darker and larger and the nipple may become erect, or stick out.
It’s common for one breast to develop faster than the other. Over time it should even out, however many adult women find their breasts differ very slightly in size. This is completely normal.
When does breast development begin and end?
In general, breast development begins between the ages of 8 and 13.
A girl’s breasts are typically fully developed by age 17 or 18, however in some cases they can continue to grow into her early twenties.
How big will my breasts get?
Your breast size is primarily determined by heredity.
Because breasts contain fat cells, a girl’s breasts size will increase with weight gain.
Why do my breasts change during my period?
Changes in hormones during your monthly period can cause changes in your breasts.
These monthly changes may include swelling, pain, tenderness and in some cases changes in breast texture, with the breasts feeling more lumpy.