Epidemiology of abortion.

The ways in which the concepts of epidemiology can be applied to the problems of abortion are reviewed. What epidemiology is and what it is not is explained, and some of the studies done on abortion are used to illustrate how epidemiology can be applied to the speciality of gynecology and obstetrics. Epidemiology is the study of health problems that occur in groups of human beings as well as the factors influencing these problems. The practice of epidemiology has epidemiologic surveillance as its foundation. Epidemiologic surveillance -- the continued watchfullness over both the distribution and the trends of incidence of a health problem -- requires the systematic collection, consolidation, and evaluation of reports about the problem. Epidemiology is concerned with the establishment of associations between events, e.g., health problems following abortion and factors that influence those events. The epidemiologic surveillance of abortion includes the practice of abortion -- the counting of cases and abortion mortality. In 1977 official reports of legal abortions indicated that more than 1 million such abortions had been performed, and the most recent data available show a continued increase in the annual account of these problems. Abortion mortality has declined substantially since the 1973 Supreme Court decision. Epidemiologists go beyond surveillance when they study specific problems observed as a result of surveillance of other data. The role of the IUD in septic spontaneous abortion deaths was identified with an observational approach. The concepts of epidemiology can also be applied to clinical studies. The clinical practice of 2nd trimester abortion posed problems that have been thoroughly investigated using comparative clinical studies. By showing that dilatation and evacuation is a safe method of 2nd trimester abortion and by quantifying the association between IUD use and septic spontaneous abortion deaths, epidemiology has made worthwhile contributions to the practice of obstetrics and gynecology.