After IVF transplantation, it may be due to the stimulation of breast vasodilatation after the elevation of progesterone and estrogen in the body on the third day, thus causing breast swelling and pain. After in vitro fertilization, progesterone will be taken orally to protect the fetus, and at the same time, endogenous progesterone and estrogen will be produced continuously, and both endogenous and exogenous progesterone and estrogen can stimulate the breast, such as to cause a series of processes such as expansion of capillaries in the breast, fat accumulation in the breast, which will lead to the secondary development of the breasts, resulting in breast swelling and pain. This is a physiological phenomenon associated with elevated levels of estrogen and progesterone, the patient can be relieved by hot compresses, local massage, if the pain is too much, the patient can seek medical attention, under the guidance of the doctor to carry out the appropriate medication, do not blindly use drugs.