Tubal pregnancy and the risk of subsequent infertility.

One hundred forty-one women with tubal infertility, all of whom had been pregnant at least once before, were interviewed concerning their reproductive, contraceptive, medical, and sexual histories. Their responses were compared with those of a control group of 467 fertile women. A higher percentage of cases (13%) than controls (1%) had had a tubal pregnancy. From these percentages, we estimate that 92% of tubal infertility in women who have had a tubal pregnancy results from tubal pregnancy itself or factors that predisposed to its occurrence. We also estimate that approximately one-fifth of women who suffer a tubal pregnancy will subsequently be infertile because of a tubal abnormality. After controlling for the joint effects of several known risk factors for tubal pregnancy that independently predispose to infertility (eg, a history of pelvic inflammatory disease), the relative risk of tubal infertility associated with tubal pregnancy was 15.0 (95% confidence interval 5.2-43.6). However, because we had no sensitive indicator of antecedent tubal disease, we were extremely limited in our attempt to determine the extent to which this association was actually due to the consequences of the tubal pregnancy itself.