We hope this information will help you to understand the normal development and ageing process of the breast and the normal changes that can occur throughout your life. It will also help you to be breast aware, so you notice any changes that are unusual for you.
While most breast changes will be benign (non-cancerous), detecting a change early means that if cancer is diagnosed any treatment may be more successful.
The breasts (mammary glands) are a pair of glandular organs that produce milk in response to the hormonal changes of childbirth. They’re mainly made up of fatty tissue, which starts high on the front of the chest and extends down and around into the armpit. They are supported by ligaments and large muscles.
Each breast has 15 to 20 lobes with a number of lobules and ducts surrounded by fatty and supportive tissue. Each lobule has about 30 major ducts that open on to the nipple. The darker area of skin around the nipple is called the areola. At the edge of the areola there are large glands that produce fluid to lubricate the nipple.
In each armpit there are about 20 to 30 lymph nodes (glands), which drain fluid from the breast. These form part of the lymphatic system that helps the body to fight infection.
It’s common and perfectly normal for one breast to be larger than the other. The nipples usually point forward, although they may look different on each breast. It’s not unusual for one or both nipples to be turned inwards (inverted). This can be present from birth or can happen when the breasts are developing. The nipples themselves are hairless, but some women may have a few hairs around the areola.
A small number of women have an extra breast or pair of breasts. These are usually in the lower armpit and are known as accessory breasts. Some women have an extra nipple or nipples. These are usually below the breast or above the belly button. Accessory breasts and extra nipples aren’t usually a problem and don’t need to be removed.
The breasts are constantly changing from the time of puberty through adolescence and the childbearing years and into the menopause, affected by changing levels in the female hormone oestrogen.
For most girls, breasts start to develop around the age of nine to 11, but it can be earlier or later. It’s not unusual for the breasts to grow at different rates. Breast lumps can occur while the breasts are developing. These are always benign and don’t usually need any treatment once they have been diagnosed.
Just before a period, your breasts may become larger, tender or feel a bit lumpy
Once the breasts have developed, changes linked to the monthly menstrual cycle (cyclical breast changes) are common. Just before a period, your breasts may become larger, tender or feel a bit lumpy. After a period, this lumpiness becomes less obvious or may disappear altogether (although some women may have tender, lumpy breasts all the time). Many women also experience breast pain linked to their menstrual cycle (cyclical breast pain).
During pregnancy the breasts get much larger as the number of milk-producing cells increases. The nipples become darker and may remain that way after you’ve given birth.
Around the menopause lumps are common. These often turn out to be breast cysts (benign fluid-filled sacs).
Breast tissue also changes with age. It begins to lose its firmness and the milk-producing tissue is replaced by fat, making the breasts sag. This is more noticeable after the menopause, when oestrogen levels fall. As you grow older, your breasts may change size too. If you take HRT (hormone replacement therapy) your breasts may feel firmer and sometimes quite tender.
This article was last medically reviewed by Dr Trisha Macnair in August 2005.
First published in November 1997.