Mastitis is primarily caused by a blockage in the milk ducts of the breast, which leads to milk backing up and causing inflammation. This blockage often occurs when the breast does not empty completely during feedings, resulting in clogged ducts and engorgement
. The most common cause is hyperlactation or an oversupply of milk, which puts pressure on the milk ducts and narrows them, leading to swelling and inflammation known as inflammatory mastitis. This condition can then progress to bacterial mastitis if bacteria enter through cracks or sores in the nipple, causing infection
. Additional risk factors and causes include:
- Sore or cracked nipples that allow bacteria to enter
- Poor breastfeeding technique or irregular nursing/pumping schedules leading to milk stasis
- Wearing tight bras or seat belts that compress the breast and restrict milk flow
- Smoking, which damages breast tissue and increases infection risk
- Stress, fatigue, poor nutrition, and underlying health conditions such as diabetes or a weakened immune system
- Breast trauma, nipple piercings, or skin conditions like eczema
- Changes in the breast microbiome caused by antibiotics or exclusive pumping can also contribute to inflammation and infection
In summary, mastitis results from milk duct blockage and milk stasis, often complicated by bacterial infection entering through nipple damage, with various lifestyle and health factors increasing susceptibility
