Ectopic pregnancy and prior induced abortion.

We compared the prior pregnancy histories of 85 multigravid women with an ectopic pregnancy and 498 multigravid delivery comparison subjects. We found a relationship between the number of prior induced abortions and the risk of ectopic pregnancy: the crude relative risk of ectopic pregnancy was 1.6 for women with one prior induced abortion and 4.0 for women with two or more prior induced abortions; however, use of multivariate techniques to control confounding factors reduced the relative risks to 1.3 (95 per cent confidence interval, 0.6-2.7) and 2.6 (95 per cent confidence interval, 0.9-7.4), respectively. The analysis suggests that induced abortion may be one of several risk factors for ectopic pregnancy, particularly for women who have had abortions plus pelvic inflammatory disease or multiple abortions.