Breast swelling and pain and delayed menstruation are usually caused by the following reasons: First, if the condition occurs in women of childbearing age, no contraceptive measures are taken in daily life to rule out the possibility of pregnancy. If pregnant, the increase in estrogen will lead to localized breast swelling and pain and no menstruation. Secondly, the delayed menstruation may be caused by the use of certain drugs, such as birth control pills, which can lead to changes in the menstrual cycle and delayed menstruation, and birth control pills are a combination of estrogen and progestin, so they often cause localized swelling and pain in the breasts. Third, may be caused by endocrine disorders, may be this period of stress caused by endocrine disorders, so that the menstrual period is delayed, breast pain, you can take free of charge pill regulation.