IUDs and Ectopic Pregnancy

To the Editor: The review of Xu Xiong, Pierre Buekens and Elisabeth Wollast’ on IUD use and the risk of ectopic pregnancy is an interesting attempt to analyze disparate material covering a wide time span and global data. The two conclusions that 1) with an odds ratio of 1.06 “Current IUD use did not enhance the risk of ectopic pregnancy” among non-pregnant women and 2) with an odds ratio of 1.40 “Past IUD use could slightly increase the risk of ectopic pregnancy” (p. 32) are, however, both without firm referents. If as stated on p. 31 “There were, however, no statistically significant differences found in the risk of ectopic pregnancy between different types of IUDs” in two reviews,2,3 the quoted odds ratios would, nevertheless, vary over time and by place. Each odds ratio would depend on the proportion of non-pregnant women who use contraception, and the type of contraceptive used. The smaller the proportion of sexually active women of reproductive age using contraception, the higher the risk of ectopic pregnancy in that referent group. This is because the non-contracepting group has no protection against ectopic pregnancy. Further, generally, the more effective the methods used in protecting against pregnancy, the lower the risk of ectopic pregnancy, as indicated by Vessey in 19764 and by Franks et a1.5 erence group. Some contraceptive methods provide better protection than do many IUDs. The Copper T380 and other devices with large copper surface areas and a levonorgestrel IUD releasing a rated 20 pg/d, on the other hand, appear to provide protection against ectopic pregnancy that is comparable to the protection given by the most protective methods.