Ectopic pregnancy in relation to previous induced abortion.

Women who were hospitalized for ectopic pregnancy in five hospitals in King County, Washington, were interviewed concerning history of induced abortion. For comparison, women who delivered a live-born child during this same time period were also interviewed. Relative to women who had never undergone an abortion, the risk in those who had was increased to a modest degree, but this increase could well have been the result of chance (relative risk, 1.4; 95% confidence interval, 0.7 to 2.6). For women who had two or more abortions, the relative risk was 1.8 (95% confidence interval, 0.5 to 7.1). Our results suggest that legal abortion as performed during the past decade in the United States does not carry a large excess risk for future ectopic pregnancy, but larger studies will be needed in order to determine more precisely the magnitude of any excess that does exist.