The enlargement of female breasts after pregnancy is a physiological phenomenon that will shrink back after giving birth and stopping breastfeeding. After pregnancy, the estrogen and progesterone in the body will increase, and estrogen stimulates the development of mammary ducts and progesterone stimulates the development of mammary alveoli, all of which will increase the size of the breasts. After delivery, stimulated by the lactogen in the body, the breasts will continue to increase in size and secrete milk, and the baby will suck on the nipple and stimulate the nipple to increase milk secretion, which will also continue to increase the size of the breasts, but these are all physiological phenomena. However, these are physiological phenomena, and when lactation stops and hormone levels return to stability, the breasts will relatively shrink. Most women who have balanced nutrition and are not over-nourished or over-obese will return to their pre-pregnancy state. It is important for women to keep their minds at ease, have balanced nutrition and be in a happy mood to have a baby.