For a more detailed explanation, you can go to <a href="http://www.cdc.gov/mmwr/preview/mmwrhtml/mm4838a2.htmIn">http://www.cdc.gov/mmwr/preview/mmwrhtml/mm4838a2.htmIn</a> my own family history, I have many ancestors and relatives past and present who have lost multiple children under the age of l year old to childhood diseases, pneumonia, cancer and other factors.