Effect of the venereal diseases epidemic on the incidence of ectopic pregnancy -- Implications for the evaluation of contraceptives

Abstract

This paper identifies a basis for quantifying the risk of ectopic pregnancy in pregnancy seekers and in users of the major means of contraception, with and without prior tubal infection. The doubling, in U.S. in recent years, of both numbers of ectopic pregnancies and the prevalence of nonsurgical sterility is correlated with the epidemic of gonorrhea and other sexually transmitted, salpingitis-producing diseases. The risk of ectopic pregnancy in women who have once had salpingitis is shown, on the basis of Weström's landmark prospective study and many retrospective studies, to be approximately 10-fold that of normal women. Fertilization-preventing contraceptives reduce uterine and ectopic pregnancies in the same proportion and in both categories of users--that is, in normal-risk and high-risk (post-salpingitis) women. Intrauterine contraceptives, however, markedly reduce uterine pregnancies, but have little effect on the incidence of ectopic pregnancy. Among IUD users, therefore, the incidence of ectopic pregnancy will be disproportionately great in relation to the fraction of high-risk women in the population of users. This disproportionate influence of prior salpingitis may confuse the comparative evaluation of contraceptive safety because the proportions of normal-risk and high-risk women probably vary widely, since public health data show extremely wide geographic differences in the incidence of gonorrhea -- the best known but not the only sexually transmitted, salpingitis-producing disease.