Breast swelling and pain a week before menstruation may be related to menstruation due to increased estrogen during the latter half of the menstrual cycle, leading to breast or nipple swelling and pain. If these symptoms occur outside of the menstrual period, it may indicate a breast condition such as fibrocystic breast disease, mastitis, or nipple infection. In such cases, it is necessary to visit a hospital for breast examinations like breast ultrasound or mammography to diagnose the condition. Generally, symptoms may relieve or disappear after menstruation, but breast pain can also be caused by local inflammation of the breast, and inflammation of the nipple can also cause swelling and discomfort. If symptoms are significant and accompanied by pain, it is advisable to seek medical attention promptly to avoid delaying the condition, and self-medicating should be avoided. On the other hand, during the early stages of pregnancy, a significant rise in hormones can also cause breast swelling and pain. Therefore, if there is a question about an impending menstrual cycle, it is advisable to undergo necessary tests to determine, and if there has been sexual intercourse for half a month, pregnancy can be confirmed through a blood test.