"Several hormones, including estrogens, progesterone, androgens, prolactin, sex hormone-binding globulin (SHBG) (17), and IGF-1 (18), have been related to an increase or decrease in breast cancer risk. Concentrations of follicle-stimulating hormone and luteinizing hormone increase during puberty, and thus are necessary for mammary gland development (3).
Estrogens (17/3-estradiol being the most potent) increase cell proliferation in the mammary epithelium; progesterone causes alveolar cell growth of the epithelium after estrogen-primed breast cell proliferation and differentiation; prolactin stimulates and maintains lactation in the estrogen-primed breast (19); and IGF-1 stimulates a mitogenic response in mammary epithelial cells and causes cell proliferation (20). Androgens, on the other hand, depress mammary cell growth (19)."
"Among present oral contraceptive users, larger breast sizes were significantly associated with higher prolactin and luteinizing hormone levels and lower follicle-stimulating hormone levels during cycle days 5-10. During cycle days 18-23, breast size correlated with a low level of endogenous progesterone.
In nonusers, the constitutional parameters body mass index, height, and weight were significantly positively correlated with breast size.
Among the nonusers, the strongest hormonal determinant of breast size during the follicular phase was IGF-1. In the luteal phase, both high 17/3-estradiol and high progesterone
Among nonusers in the multivariate models, luteinizing hormone showed a positive relation to breast size, and follicle-stimulating hormone showed a negative relation. In the univariate correlation models, it appeared that follicle-stimulating hormone works in opposite directions in relation to breast size among former and never users.
High prolactin levels during cycle days 5-10 and low endogenous progesterone levels during cycle days 18-23 were related to larger breast sizes among current users. This could imply that women who are especially sensitive to the synthetic estradiol and progestin in oral contraceptives react with a larger increase in prolactin levels and a larger decrease in endogenous progesterone levels than other women. If this subgroup of women shows a more pronounced reaction regarding changes in their hormone levels, they may also react with a more pronounced increase in breast size.
The relation between a low progesterone level and large breast volume could suggest that oral contraceptives containing primarily progestin increase breast volume more, since women in this study used low dose oral contraceptives."
http://aje.oxfordjournals.org/content/145/7/571.long
After reading this article i'm a bit confuse right now. The study correlated breast size, the use of oral contraceptives, hormones in menstrual cycle and body mass index.
From what i understand..
In oral contraceptive users
Larger breast sizes = 5-10 days cycle - higher prolactin and luteinizing hormone + lower follicle-stimulating hormone. 18-23 days - low level of endogenous progesterone.
In non users or former users
Larger breast sizes = body mass index + 5-10 days - high IGF-1. 18 -23 days - both high 17/3-estradiol and high progesterone + luteinizing hormone showed a positive relation to breast size, and follicle-stimulating hormone showed a negative relation.
But then this conclusion that i can't understand the meaning for oral contraceptive users?!?
"The relation between a low progesterone level (18-23days) and large breast volume could suggest that oral contraceptives containing primarily progestin increase breast volume more, since women in this study used low dose oral contraceptives."
(In this study, women that are current users of oral contraceptives have larger breast sizes)
So what can we take from this study for NBE? Women with low progesterone during luteal phase and high prolactin and lower FSH during follicular phase, and using oral contraceptives have bigger breasts?! And in nonuser women with high high IGF-1 during follicular phase and high estradiol and progesterone in luteal phase have bigger breats?! Luteinizing hormone showed a positive relation to breast size, and follicle-stimulating hormone showed a negative relation.
