EVALUATION OF INDUCED-ABORTION AS A RISK FACTOR FOR ECTOPIC PREGNANCY- A CASE-CONTROL STUDY

Objective. To assess the risk of ectopic pregnancy after one or more i nduced abortions. Design. Population-based case-control study. Methods . We studied all women who had a histologically verified ectopic pregn ancy in one Norwegian county between January 1, 1987, and December 31, 1990. We identified population-based control sets of women among part icipants in the second Norwegian fertility study (1988-1989). Gravida women 20-39 years of age, who were not using contraceptives and had be come spontaneously pregnant, were eligible for analysis. The final ana lyses included 174 women with ectopic pregnancy, 115 pregnant control women and 227 nonpregnant control women. Statistical methods. Chi-squa re test and unconditional logistic regression. Results. Fifty-three (3 0.5%) of women with ectopic pregnancy, 18 (15.7%) of pregnant control women and 51 (22.5%) of nonpregnant control women had had one or more previous induced abortions. The adjusted odds ratio of ectopic pregnan cy among women with one previous induced abortion was 1.3 (95% confide nce interval; 0.9 to 1.8) and 1.2 (95% CI; 0.8 to 1.7) compared with p regnant and nonpregnant control women, respectively. Among women who h ad two or more induced abortions, the adjusted odds ratio of ectopic p regnancy was 0.2 (95% CI; 0.04 to 0.9) compared with pregnant control women and 1.8 (95% CI; 0.4 to 7.8) compared with nonpregnant control w omen. When we used the outcome of the most recent pregnancy, birth as reference, we found no association between an outcome of induced abort ion and subsequent ectopic pregnancy regardless of whether the control women were pregnant. Conclusion. We found no association between indu ced abortion and subsequent ectopic pregnancy Women who had induced ab ortions were characterized as having several other risk factors for ec topic pregnancy.