Pregnant nipples can be enlarged, darkened, and easily erected. The areola becomes darker and the sebaceous glands on the areola become enlarged and form small scattered nodular elevations called Montserrat’s nodes. Changes in the breasts usually begin to appear at 56 days of pregnancy. Due to the influence of various hormones such as pituitary lactogen, placental prolactin, estrogen, progesterone, growth hormone and insulin, breast ducts and alveoli proliferate and fat is deposited during pregnancy, and it is normal for pregnant women to feel swelling, tenderness and tingling sensation in their breasts. Although a large amount of hormones are involved in the development of the mammary glands during pregnancy to prepare for lactation, there is no secretion of milk during pregnancy, which is mainly related to the large amount of estrogen and progesterone that inhibit milk production. At the end of pregnancy, especially near the time of delivery, several drops of thin yellow liquid can overflow from the breast when squeezed, which is normal, and lactation can occur when the newborn sucks on the nipple after delivery.