It is known that breast milk brings great benefits to the children and to the mother's body, regardless of whether she is breastfeeding directly or pumping milk. Despite this, many mothers wonder what will happen to their body shapes after stopping breastfeeding and how this varies from direct breastfeeding to the pump method.
Like all aspects of motherhood, changes in the breast vary from mother to mother. Breast size almost always changes during breastfeeding. Breast milk production dilates the skin of the breast, which can cause sagging of the breast at a later period (however, this also depends on the genes).
However, the use of a breast pump can cause changes in the nipple area, such as their expansion, as the pump has a higher suction power than children. Breast pumping should never cause chest damage and if this happens to you, try changing the size of the pump head, try a lower power, or check with your doctor for any other health problems.
Source: Women's Health