They’re right there on our chest—AA or DDD, perky or pendulous, nipples pale pink or dark brown—and yet most of us don’t give our breasts much thought day to day. But we should. Here’s what the look and feel of your dynamic duo can tell you about your health.

If your breasts are growing, it’s likely due to weight gain (because breasts are made up of mostly fat cells, in addition to glandular tissue), pregnancy (as milk ducts ramp up for breast-feeding), birth control pills, and/or hormonal changes related to your menstrual cycle (they’re very sensitive to shifts in estrogen and progesterone). No need to worry, though you might need to buy new bras.

If your breasts are growing, it’s likely due to weight gain (because breasts are made up of mostly fat cells, in addition to glandular tissue), pregnancy (as milk ducts ramp up for breast-feeding), birth control pills, and/or hormonal changes related to your menstrual cycle (they’re very sensitive to shifts in estrogen and progesterone). No need to worry, though you might need to buy new bras.