Breast swelling is not necessarily pregnancy, but can also be seen during menstruation or premenstruation, breast disease, etc. If breast swelling is accompanied by a history of menopause, it may be due to pregnancy, otherwise other factors need to be considered.1. Pregnancy: Breast tissue is easily affected by changes in the levels of estrogen and progesterone, which are at high levels and can lead to breast swelling and pain, and some women may also experience breast enlargement and nipple or areola coloring. The estrogen and progesterone levels in the body can increase significantly after pregnancy, which in turn induces breast swelling; 2, menstruation or premenstruation: breast swelling is not necessarily caused by pregnancy, but may also be caused by hormonal changes in the body during menstruation. Generally, before the onset of menstruation, estrogen levels can rise to the highest state, causing stimulation of the breast tissue and swelling pain, some women in the premenstrual or menstrual period can appear such symptoms. But the general duration will not exceed 7 days, breast pain can disappear gradually with the end of the menstrual period; 3, breast disease: such as suffering from breast hyperplasia, acute and chronic inflammation of the breast, can also trigger the performance of breast swelling, mostly seen in women of childbearing age, generally need to carry out imaging examinations of the breast to clarify the diagnosis, in order to carry out the corresponding treatment.