If your period is delayed for five days and your breasts are swollen and painful, it may be caused by pregnancy, endocrine disorders, PMS and other reasons. 1. Pregnancy: If a woman has intercourse during ovulation and does not take contraceptive measures, she may become pregnant. After pregnancy, due to the significant increase in estrogen and progesterone in the body, it is easy to cause breast swelling and pain. After pregnancy, the uterine lining will not continue to shed, which will cause delayed menstruation. As HCG in the urine is not yet significantly elevated in early pregnancy, pregnancy may not be detected. 2. Endocrine disorders: endocrine disorders can easily lead to excessive secretion of estrogen and low secretion of progesterone. Uneven hormone levels can lead to breast tenderness and pain, delayed menstruation, and can be accompanied by mood changes such as depression, irritability, and so on. 3. Premenstrual Syndrome (PMS): may be related to ovarian hormone imbalance, psychosocial factors, etc., which leads to a woman’s menstrual period delayed for five days, breast swelling and pain, but can not detect the pregnancy of the situation. If a woman’s period is delayed for five days, her breasts are swollen and painful, and she is not pregnant, it is recommended that she seek medical attention in a timely manner, and under the guidance of a doctor, complete the relevant examinations, identify the cause of the disease, and treat the symptoms.