The best time for a mammogram is 7-10 days after menstruation when the breasts are not affected by hormones. The breast changes with the menstrual cycle, and before menstruation, the hormone level in the body increases, so there is a greater chance of misdiagnosis, while 7-10 days after menstruation, the estrogen and progesterone levels have significantly decreased, the breast duct cells shrink and fall off, edema subsides, and the volume of the breast follicles and lobules shrinks significantly. If a breastfeeding woman needs to undergo mammography, she should empty her breast milk before the examination to improve the accuracy of the examination and to prevent milk overflow caused by the examination. Mammography is the main form of breast cancer screening and is recommended once every 1-2 years for women over the age of 35 and once a year for women over the age of 45.