For breasts, it's off to the races. The milk production and delivery system begins to flourish immediately. Though hardly noticeable outwardly, all that interior activity is quickly felt. Cool compresses may relieve breast tenderness. Blood flow to the breasts steps up, too, and fatty tissue builds up to surround and cushion the expanding network of milk ducts and glands.
Nipples become more erect and more sensitive.
The areola, the pigmented circle around each nipple, enlarges and darkens, so that in about eight months it will offer a good target for a hungry infant. Montgomery's glands, a ring of small bumps on the areola that secrete an antibacterial substance, grow more prominent. Overall breast size increases, sometimes dramatically. Veins may be noticeable on the surface. Feelings of tenderness, heaviness, and fullness may continue.