This document discusses common causes of breast tenderness during pregnancy and after delivery. Mild breast pain is quite common during pregnancy due to changes like hyperplasia, hyperemia, and duct formation. More severe tenderness can be caused by mastitis, breast abscess, or engorgement after delivery. Mastitis is marked by redness, swelling, tenderness and fever, and is usually treated with hot compresses, antibiotics and postponing breastfeeding from the affected breast until the inflammation subsides. Breast abscesses require incision and drainage in addition to antibiotic treatment.