Women age 40 and older should have mammograms every one or two years. However, the likelihood of developing breast cancer is higher if a close blood relative has been diagnosed with the disease, especially if they were diagnosed before the age of 50. Likewise, women who began having their periods before the age of 12 or who went through menopause after the age of 55 are at higher risk, as are women who had their first child after age 30 or who never had a child. If you believe you may be at a higher risk, ask your physician when you should start being examined.