Over weeks, or sometimes even months, when there is no more exposure to the hormones, the breast tissue begins to shrink and eventually.
It's normal for newborn babies (boys and girls) to have swollen, enlarged breasts and/or lumps under the nipple. What are breast lumps like in a newborn baby? When will breast lumps in a newborn baby go away?.
Baby girls and boys will have a small breast bud that can be felt for a few weeks after they are born. These buds of tissue will become the breast.