If a woman has intercourse during ovulation, it has led to the successful union and implantation of a fertilized egg. In this case, the breasts will feel distinctly swollen and painful, and there will be an erection of the nipples, as well as an increase in the color and size of the areola. This is because after the fertilized egg has successfully implanted, the ovaries continue to produce estrogen and progesterone, which stimulates the development of the mammary glands and ducts. This is why women experience a constant feeling of breast swelling and pain after pregnancy. This feeling will last until about seven months of pregnancy, and when the seventh month of pregnancy is over, there will be a small amount of yellow discharge from the nipples, which is the physiological nature of milk secretion and discharge. Therefore, if a woman has breast tenderness for more than 18 days, she should use an early pregnancy test to confirm whether she is pregnant.