There is zero scientific evidence to support the idea that wearing a tight-fitting bra causes mastitis or plugging. The vast, vast majority of the time, someone experiencing mastitis does not have an infection and is merely perceiving localized breast engorgement and edema (soft tissue swellng). In the same way that you can’t cause an intestinal blockage with a tight belt or a breast cyst with tight-fitting bras, you can’t cause any other internal breast pathology with a bra, either.
Most lactating women enjoy the comfort of a good bra; wearing one also reduces pain and swelling in the lower parts of the breast. If you don’t have large breasts or otherwise don’t want to wear a bra, that is also perfectly fine. It’s mostly important to know that you will NOT harm yourself by wearing a bra if you want.
