Induced abortions, contraceptive practices, and tobacco smoking as risk factors for ectopic pregnancy in Athens, Greece. A case-control study of the role of induced abortion and other factors on the subsequent occurrence of ectopic pregnancy was undertaken in 1986-1987 in Athens, Greece, where a similar study 20 years ago found a tenfold risk of ectopic pregnancy among women with one or more illegal induced abortions. Seventy women residents of Athens, consecutively admitted to the major state maternity hospital with a diagnosis of ectopic pregnancy, were individually matched with women with a newly diagnosed pregnancy of the same order as the ectopic index pregnancy. Two control women were found for each of 63 cases, but only one control for each of the remaining seven cases. All cases and controls were interviewed by the same qualified obstetrician. Statistical analysis was undertaken with stratification of individual matched triplets and pairs, as well as through conditional multiple regression procedures. The relative risk of recurrence of an ectopic pregnancy was 6.39 with 95% confidence interval (CI) 1.96-21.04. Miscarriages did not increase the risk of ectopic pregnancy. The relative risk for subsequent ectopic pregnancy among women with one or more induced abortion, compared to women without such abortions, was 1.87 (CI 0.84-4.16) controlling only for the matching factors, and 1.71 (CI 0.69-4.27) when marital status (a possible selection factor) was also accounted for in the conditional logistic regression. There was no evidence for increasing risk with increasing number of induced abortions. Past use of an intrauterine device (IUCD) was associated with a relative risk of 3.89 (0.72-21.02); the relative risk increased with the duration of use of the IUCD. 