Delayed menstruation breast swelling and pain may be pregnancy, but also does not exclude endocrine disorders, premenstrual syndrome and other possibilities, need to test HCG. 1. Pregnancy: If the patient had intercourse during ovulation and did not take contraceptive measures, then the possibility of pregnancy is relatively large, at this time the body estrogen and progesterone significantly higher, so it causes breast swelling and pain. The delay in menstruation is due to the fact that the uterine lining does not fall off in time after pregnancy. If the patient suspects that she is pregnant, it is recommended that she take an early pregnancy test as soon as possible to determine whether she is pregnant. 2. Endocrine disorders: If endocrine disorders, the imbalance of estrogen and progesterone secretion may lead to delayed menstruation, and at the same time, estrogen and progesterone disorders may cause breast capillary congestion, which may lead to breast swelling and pain. 3. Premenstrual syndrome: women’s monthly menstruation advance or delayed no more than 7 days is a normal phenomenon, before the onset of menstruation due to changes in the body of estrogen and progesterone, can also cause symptoms of breast swelling and pain, may be premenstrual syndrome. Once a woman realizes that her period is delayed and her chest is swollen and painful, she may be pregnant, or it may be due to other reasons, so she should be vigilant and consult a doctor to check her HCG in a timely manner.