The Breast: A Guide

breastsA woman’s breast are the most obvious signs of her sexuality as well as being an important erogenous zone. But a primary biological function is to provide milk to feed and nourish a baby. We take you through what’s happening.

From their early appearance in the developing foetus until puberty, the breasts of both sexes, remain virtually identical. Until the age of ten or eleven the chest wall is flat and both boys’ and girls’ breasts appear as small pink nipples ringed by an area of rosy nodular skin, known as the areola. At about this age, though, the areola bulges outwards very slightly. After this, the breasts of males develop no further, although hormonal changes during puberty may cause temporary breast swellings.

It is only when a girl matures into a woman and her breasts start preparing for their primary function – to produce milk to feed and nourish a baby – that differences between males and females start to appear.

For a girl, as puberty progresses, breast development goes much further. The ovaries, which have so far lain dormant, begin to produce the hormones oestrogen and progesterone. Between them, these two hormones are responsible for causing more of the changes that make a girl into a woman. Later, they regulate and maintain the cycles of fertility and have vital roles in pregnancy and all the changes associated with it.


At the first budding of puberty, oestrogen controls the distribution of extra fat to specific sites of the body – the hips, bottom, thighs and the breasts. At the same time the nipples enlarge and milk ducts begin to develop, growing inwards from the nipple.

The progesterone encourages the ends of these milk ducts to swell out into lobes. These lobes are made up of many smaller lobes, called lobules, which contain the glands that will eventually make milk.

It takes about 18 months from the appearance of the first swellings on the chest to the point at which the internal structure is complete. But the breast does not usually reach its adult shape until the mid-teens. Breast size is largely governed by how much fat surrounds the milk-producing structures. The fat protects the milk ducts and glands.

Many women find that their breasts become tender just before a period. This is caused by extra progesterone circulating in the body, which causes the breasts to swell. This is perfectly normal but in some women the breasts may also become very tender and uncomfortable.

Most women will find this diminishes with the onset of menstruation but in some cases the breasts remain tender and feel lumpy. This is because the fluids that have built up fail to drain away. Pregnancy will probably cure the condition, but this is a rather drastic remedy. Medical help should be sought so treatment can be given.

the breastIn addition to this change most women find that the shape, size and appearance of their breasts will alter considerably during their lifetime. The greatest changes take place when the body goes through major alterations in hormone levels. After puberty, these times are during pregnancy, breastfeeding and the menopause.


It does not matter what size a woman’s breasts are to start with; they will increase in size during pregnancy. This is because the placenta, which attaches the baby to the mother’s womb, produces large amounts of the hormones progesterone and oestrogen. These cause the breasts’ glandular tissue to enlarge and true milk-producing cells are formed. By the end of pregnancy the breasts have become an efficient, milk-producing organ.

The increase in breast size, however, is not only due to the increase in the size of the milk-producing lobules. Large amounts of fat are also deposited in the breast. The actual breast weight increase is about a kilogram.

For the majority of women the breasts return to their non-pregnant size and shape once breastfeeding has finished. In some cases the breasts are actually smaller than they were before. However, this is simply because the fat reserves in the breast have been used up. These are soon replaced as long as the mother has a balanced diet.

An unmistakable sign of pregnancy is the darkening of the areola. This goes from pink to brown, and by the second month becomes very dark. In some women this happens so soon after conception that it is the sign by which they know they are pregnant even before a period has been missed.


After the birth, the areola and the nipple will become lighter, but never as pale as before. The sebaceous glands that produce the oils to keep the nipple supple, become more prominent and pimple-like and are then know as ‘Montgomery’s tubercles’. While a woman is breastfeeding these tubercles secrete a lubricating fluid to help prevent the nipple from cracking.

After pregnancy, the skin of the breasts will almost certainly show stretch marks where it has had to allow for the increase in size. These normally fade to faint silvery lines.

Detecting problems

Because of the sexual context in which breasts are regarded it can be hard to think of them as functional organs which require care and attention.

Some women are terrified to examine their breasts in case they find a lump. But a lump does not always indicate breast cancer. In any event, this type of cancer, provided it is detected early, does not always mean the removal of the breast.

The best time for a woman to examine her breasts is a day or two after her period has stopped. This is when the breasts are at their smallest and lumps are easier to spot. It is also a good idea to know how the breasts feel at other times during the menstrual cycle – after a few months the woman will get to know what should or should not be there at any give time. Any lumps should be reported immediately to a doctor.

It is also important to watch for and report any dimpling or puckering of the skin, any fluid, blood or pus from the nipple, or sudden inturning of a nipple that has previously been erect.

Posted in Health, Your Body