Pregnancy hormones do some wild -- and unexpected -- things to your body, including causing your skin cells to produce more pigment. That explains why your areolas (the skin around your nipples) have suddenly become darker and grown larger. You may also notice that this area looks bumpier than usual. That's because of the growth of small glands (called Montgomery's tubercles) that will eventually secrete an oily substance to protect your nipples from becoming dry and cracked during breastfeeding. Though they can seem odd at first, all these breast changes are completely normal and just a sign that your body is preparing to nurse your baby. After you're done breastfeeding, the color and size of your nipples will most likely return to normal.