Induced abortion and ectopic pregnancy in subsequent pregnancies.

In a prospective study the rate of ectopic pregnancies of women with prior induced abortion was contrasted to two sets of comparison groups: a large set of unmatched observations and a smaller subset of matched and refined data. The crude rates of ectopic pregnancy among 4004 abortion and 98,316 control pregnancies, excluding repeat pregnancies of the same women, were 0.57% and 0.49%, respectively. No significant association was detected between history of induced abortion and ectopic pregnancy based on the chi 2 analysis on unmatched data stratified by maternal age and marital status (relative risk = 1.18, 95% confidence limits (CL) 0.57-1.79) or the multivariate logistic regression analysis on the smaller set of data (relative risk = 1.34, 95% CL 0.66-2.72). Within pregnancies of the induced abortion group the risk of ectopic pregnancy was not related to abortion procedure, use of laminaria, number of prior induced abortions, or length of gestation at time of abortion. However, there was a clear association between the presence of post-abortion infection or retained secundines and ectopic pregnancy with a fivefold increase for those pregnancies of women with a history of these complications over those without these complications within the induced abortion cohort.