Estrogen is the female hormone that kicks into gear when a girl goes through puberty. This hormone results in her developing breasts and pubic hair and prompts the start of her menstrual period. Estrogen does cause breast tissue to increase. If you are taking oral contraceptives or hormone replacement therapy (HRT) due to menopause, these drugs contain estrogen and you may notice that your breasts have gotten bigger. During pregnancy, when your body is flush with estrogen, breasts get bigger, too. Progesterone, the other female sex hormone, plays a part in breast size as well although not exactly the same role as estrogen.
What Estrogen Does
Estrogen levels increase as a woman gets ready for her menstrual period. Estrogen fires up the milk ducts in the breasts during the menstrual cycle, which makes her breasts get bigger and sometimes results in soreness and tenderness, which is referred to as mastalgia. When a woman ovulates, progesterone is produced and this causes her to retain fluids, which makes her breast tissue swell and her breasts will get bigger as a result. Working in tandem, estrogen actually increases the amount of breast tissue whereas progesterone causes the breasts to fill up with fluid, resulting in a rather noticeable size increase at times.
Contraceptives and HRT
If you are taking contraceptives or HRT and you have noticed a big change the size of your breasts, along with breast tenderness and sensitivity, discuss this with your physician. If it’s bothering you, perhaps your dosage needs to be lowered. Contraceptives that contain estrogen and progesterone can make your breasts become engorged due to edema, which is fluid retention, according to Health Services at Columbia University's "Go Ask Alice" website.
There is a difference of opinion about what happens to breasts during menopause. Some physicians maintain that a woman’s breasts shrink because of the deficiency in estrogen. When estrogen declines, skin in general becomes less elastic, thins and tends to become dehydrated, which can result in smaller, sagging breasts. However, many menopausal women will tell you that their breasts have increased in size, which may be due to weight gain or simply a shift in weight or some other factor that the researchers haven’t yet found.
According to Healthlibrary.epnet.com, if synthetic estrogen is taken in high enough doses, this can stimulate breast cell growth. However this can also lead to breast cancer, so it is not advised that a woman take synthetic hormones for the sole purpose of increasing breast size.
Some herbs and plants contain what is called phytoestrogens that mimic the estrogen a woman’s body naturally produces. When taking phytoestrogens, it is possible that you will notice an increase in breast size.