Only one hundred years ago, in even the world's wealthiest nations, children died in great numbers--of diarrhea, diphtheria, and measles, of scarlet fever and tuberculosis. Throughout history, culture has been shaped by these deaths; diaries and letters recorded them, and writers such as Louisa May Alcott, W. E. B. Du Bois, and Eugene O'Neill wrote about and mourned them. Not even the powerful and the wealthy could escape: of Abraham and Mary Lincoln's...