Just under the nipple these ducts dilate, forming reservoirs of milk during feeding. Pressure by the infant's mouth on the areola, the distinct circle of dark skin surrounding the nipple, causes milk to be ejected from the 15 to 20 ducts. Surrounding the glandular tissue is a large pad of fat cells, which give the breasts its shape. The entire breast mass extends over a large area, reaching up into the armpit. Despite the vagaries of fashion and the women's liberation movement, many women find that they do prefer to wear a brassiere - both for the sake of comfort and, hopefully, to ward off stretching and sagging.
Support is especially important during pregnancy.
Throughout pregnancy the breasts become fuller. This and tingling nipples are, for many women, among the first indications of pregnancy. The areola itself may further darken, especially in dark-haired women. Although boyish figures are promoted as fashionable, many women worry if their breasts are very small. Breast size tends to increase after the age of 35 or so, chiefly due to fat being deposited in the breast.