A computerized model that simulates reproductive events during the childbearing years of a cohort of women is used to analyze the impact of contraception and induced abortion on fertility. Four different reproductive regimens are investigated: (2) contraception only, (2) abortion only, (3) abortion as a backstop to contraception, and (4) combinations of abortion and contraception. It is concluded that in historical as well as in modern populations, levels of fertility near replacement are unlikely to be obtained without the use of induced abortion.
PIP: A computer simulation was developed to test the effects of several variables on the total fertility rate (TFR) and on the total abortion rate (TAR). Although several input variables can only be quantified within wide margins of error, the simulation was at least compatible with the following contentions: 1) Regardless of its legal status, abortion is used with similar frequency in all countries that have similar patterns of marriage, contraception, and fertility. 2) It is unlikely that any population has ever attained a low level of fertility without the use of induced abortion. 3) More widespread and effective use of contraception reduces the need for abortion; however, abortion is not likely to disappear at the levels of contraceptive effectiveness currently attained and attainable.