Breast swelling and pain may occur during the first trimester because of the rapid growth of estrogen and progesterone in the body during the first trimester, which causes the blood vessels in the breasts to expand and may cause swelling and pain. Usually it will slowly improve after two months or even three months of pregnancy and will not affect the health of your body. However, you can check yourself to rule out the presence of breast lumps or nodules. If they exist, it is suggested that you may have breast enlargement, and it is recommended that you go to the mammography department to register for treatment according to the situation. If there are no lumps or nodules on self-examination, local massage or hot compresses can be applied to relieve them. Do not stimulate the nipples as much as possible during massage or hot compresses, as this may cause uterine contractions and possibly abdominal pain or even bleeding.