Legalized abortion: effect on national trends of maternal and abortion-related mortality (1940 through 1976).

Both non-abortion-related maternal and abortion-related mortality declined prior to the Supreme Court decisions of 1973. In order to determine the effect of legalized abortion on maternal mortality, we have analyzed the secular trends in national abortion mortality ratios for 1940 through 1976, compared the trends to those maternal mortality ratios, and hypothesized reasons for differences between these trends. Between 1940 and 1950 and after 1965, deaths from abortion declined more rapidly than deaths from other causes associated with childbirth. However, between 1951 and 1965, maternal mortality related to pregnancy of childbirth declined more rapidly than abortion-related mortality. Five possible explanations exist for the more rapid decline in abortion deaths since 1965--selected underreporting, changes in coding practices, improved safety of illegal abortion, introduction of more effective contraception, and increased availability of legal abortion. We consider the last two explanations as the most likely reasons for the accelerated decline in abortion-related deaths.