New mammography regulations are now in effect, which means you’ll start seeing an explanation about your breast density on your next mammogram report. In the U.S., almost half of women over age 40 have dense breast tissue. The dense areas, as opposed to fatty tissue, show up as white, nontransparent areas on a mammogram, making cancer detection more difficult. Before these updated requirements from the FDA, breast density reporting and state regulations varied and were widely inconsistent. Now, women will receive better, easier-to-understand information about their level of breast density and what it means. Learn more about dense breasts.