Printed in U.S.A. DOI: 10.1093/aje/kwh070 Prevalence of Induced Abortion in a Reproductive Lifetime

The period total first abortion rate (TFAR) has been used to estimate the proportion of women who will experience an induced abortion in their reproductive lifetime. It is a hypothetical measure as age-specific rates currently existing will change with time. Instead, a cohort TFAR has been calculated for women born around 1955 using legal-abortion reports in South Australia to calculate first abortion rates for each year of age from 15 years to 44 years for 1971–2000, respectively, and summing these. Yearly fertility rates were also calculated for this cohort to further describe their reproductive experience. Yearly first abortion rates were also calculated for later cohorts born in 1960–1980. The 1955 cohort TFAR was 288.1 per 1,000 women aged 15–44 years. Cumulative first abortion rates at specific ages were higher for subsequent cohorts (e.g., 309.6 per 1,000 at age 40 years for the 1960 cohort). Thus, about 29 % of South Australian women born around 1955 and exposed to legal abortion throughout their reproductive lifetime experienced an induced abortion. This proportion would be higher for later cohorts of women born in 1960–1980 (e.g., at least 31 % for those born in 1960). abortion, induced; abortion, legal; age factors; demography; population; prevalence Abbreviations: TAR, total abortion rate; TFAR, total first abortion rate. The question has often been asked, “What proportion of all women have experienced or will experience an induce