Page "Breast" Paragraph 26

Because the breasts are principally composed of adipose tissue, which surrounds the milk glands, their sizes and volumes fluctuate according to the hormonal changes particular to thelarche ( sprouting of breasts ), menstruation ( egg production ), pregnancy ( reproduction ), lactation ( feeding of offspring ), and menopause ( end of menstruation ).

For example, during the menstrual cycle, the breasts are enlarged by premenstrual water retention ; during pregnancy the breasts become enlarged and denser ( firmer ) because of the prolactin-caused organ hypertrophy, which begins the production of breast milk, increases the size of the nipples, and darkens the skin color of the nipple-areola complex ; these changes continue during the lactation and the breastfeeding periods.

Afterwards, the breasts generally revert to their pre-pregnancy size, shape, and volume, yet might present stretch marks and breast ptosis.

At menopause, the breasts can decrease in size when the levels of circulating estrogen decline, followed by the withering of the adipose tissue and the milk glands.

Additional to such natural biochemical stimuli, the breasts can become enlarged consequent to an adverse side effect of combined oral contraceptive pills ; and the size of the breasts can also increase and decrease in response to the body weight fluctuations of the woman.

Moreover, the physical changes occurred to the breasts usually are recorded in the stretch marks of the skin envelope ; they are historical indicators of the increments and the decrements of the size and the volume of a woman ’ s breasts throughout the course of her life.