The other 2 arteries that bring blood to the brain, called the vertebral arteries, supply the brainstem. Plaque in the vertebral arteries is much less likely to break off and cause a stroke, but narrowing in the vertebral arteries can cause problems if the brainstem does not get enough blood flow.
A child should receive the first shot when he is between 12-15 months, and the second when he's between 4-6 years of age. If you're not sure if you have had the diseases or the vaccines (prior to 1971 it was given in three separate shots), you can get the MMR vaccine as an adult.
Most women of childbearing age were vaccinated as children with the MMR vaccine, but they should confirm this with their doctor. If they need to get vaccinated for measles, they should avoid becoming pregnant until one month (28 days) after receiving the MMR vaccine. Pregnant women who are not protected against measles should wait until after they have given birth to get MMR vaccine.