Breast tenderness after embryo transfer is usually caused by successful transfer, but it cannot be ruled out that it is caused by endocrine disorders after transfer. 1. Successful transfer: After the embryo transfer surgery, the pregnant embryo is implanted, the hormone level in the body rises, there may be breast swelling and pain. Generally speaking, after the transfer operation, you can go to the hospital for a blood test of HCG in about ten days to confirm the diagnosis. It is necessary to take blood tests for HCG and progesterone every other day to see if the doubling of HCG is normal and whether the progesterone is low. 2. Endocrine disorders: After the transplantation surgery, due to mental stress, long-term in a state of tension will be due to endocrine disorders, resulting in increased prolactin, mammary gland hyperplasia and other phenomena, which will cause breast swelling and pain. After the transplantation surgery, you need to go to the hospital in time to take blood tests for HCG, and after confirming the pregnancy, you should actively preserve the fetus under the guidance of the doctor. Avoid endocrine disorders caused by stress.