[nanakante]

The quick answer is it's likely, but the extent to which breast size increases depends both on the woman and the type of birth control pill she uses. Estrogen and progestin, the hormones found in birth control pills, often lead to an increase in breast size that generally reverses after a few cycles or when the woman goes off the pill. One reason the breasts become larger and feel engorged is because the hormones in the pill cause edema, or fluid retention. When this is the case, breasts often feel smaller during the pill-free or placebo pill week. The estrogen and progesterone in birth control pills can also lead to breast tissue growth, in which case the change in breast size tends to be more constant.