There are both physiological and pathological factors that cause breast swelling and pain in women: 1. The slight breast swelling and pain that occurs during or before and after menstruation generally belongs to physiological swelling and pain, which is related to changes in the level of technology in the body; 2. If there is no direct relationship between breast swelling and menstrual cycle, you should consider that you may suffer from breast diseases such as breast enlargement, breast fibroid, breast cyst, etc. You need to undergo breast ultrasound examination for clear diagnosis and timely treatment. You should pay attention to wearing loose and comfortable, soft and breathable underwear to avoid squeezing and stimulating your breasts.