Achy breasts are one of the earliest tip-offs that you have a baby on the way, and like many other pregnancy pains, your hormones are to blame. Throughout your pregnancy, hormones like estrogen, progesterone, and prolactin stimulate your breasts and cause the milk glands inside them to grow. (FYI, this also what's behind that wow-cleavage you're likely experiencing these days.) What you're feeling is actually growing pains as your breasts prepare for lactation, and the discomfort may come and go over the course of your pregnancy. Although there's not much you can do about it, wearing the wrong bra could make the pain worse. Get properly fitted for a more supportive bra (it may not look pretty as those skimpy lacey underwires, but it will be much more comfortable). You may find that wearing a sports bra helps. Try wearing it to bed if your breasts ache at night. If the pain is really getting to you, ask your doctor if you can take Tylenol.