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.

Hormonal issue.

A common problem is elevated levels of prolactin, which could come from a medication you’re taking (such as the pill or certain SSRI antidepressants), having an underactive thyroid, duct ectasia (a menopause-related shortening of the milk ducts), or worst case, a pituitary tumor.

A benign tumor called a papilloma can occasionally cause a bloody discharge, Maman notes. Discharge can also just mean you’re pregnant and your breasts are kick-starting the milk production factory. And milky discharge can persist for up to 2 years after you stop breast-feeding. “Most times, nipple discharge is normal but should still prompt an evaluation,” Maman says, “particularly when nipple discharge is bloody, involves only one breast, and occurs along with skin changes and suspicion of a breast mass.”