There are two conditions to consider when you have slightly swollen breasts but no painful symptoms: the first condition is breast hyperplasia, also known as lobular hyperplasia or cystic hyperplasia, which is a benign lesion. It is related to the hormone level in the body, and usually after the hormones are elevated in the body during the premenstrual period, it can lead to breast swelling. There may or may not be painful pins and needles in the breast. Ultrasound examination of the breast usually does not show any obvious masses, but only a disturbance in the internal structure of the breast. The second condition may be caused by pregnancy, also known as early pregnancy. When a patient is pregnant, the hormone levels in the body will change and the progesterone level will increase significantly, resulting in breast swelling and a feeling of enlargement and fullness. A urine HCG test can be performed to make a preliminary judgment, and if necessary, blood HCG and abdominal ultrasound can be performed at the hospital to further clarify.