Breasts will become smaller after weaning. When a woman is breastfeeding, she consumes more physical energy, the stored fat in her body disappears, and her body shape becomes thin, plus she pays no attention to breast protection during and after breastfeeding, resulting in smaller breasts. In addition, the influence of progesterone, pregnancy and puerperium, due to a large number of estrogen and progesterone, so that the mammary ducts proliferation, the number of follicles increased, the fat content increased, the breast is relatively plump. After weaning, the hormone level decreases, the mammary gland atrophies, the follicle collapses and disappears, thus the phenomenon of smaller breasts occurs. For women whose breasts become smaller after weaning, usually pay attention to the standing and walking posture, often keep the breasts straight, in order to facilitate the healthy development of the breasts, and participate in swimming sports, which will help the breasts to be beautiful.