Death rates in the 20th century fever, polio, measles, hepatitis among others. However, war, genocide and Holocausts have led to many millions of deaths throughout the century, and late in the century AIDS had already killed millions, particularly in Africa and south-east Asia. Cancer also killed millions via lifestyle and pollution generated by increased work in factories. During the 20th century, an enormous improvement in public health led to an overall decrease in death rates. Infant mortality rates and maternal mortality rates have dramatically decreased. In the early 1900s, 6-9 women died in pregnancy-related complications for every 1,000 births, while 100 infants died before they were
Decade 1960 to 1969, "the 197th decade" spans 1961 through 1970. A decade may also refer to an arbitrary span of ten years. For example, the statement "during his last decade, Mozart explored chromatic harmony to a degree rare at the time", merely refers to the last ten years of Mozart's life without regard to which calendar years are encompassed. Particularly for the 20th century, a nominal decade is often used to refer not just to a set of ten years but rather to a period roughly approximating those ten years - for example, the phrase "the sixties" often refers to