Use of Copper Intrauterine Devices and the Risk of Tubal Infertility Among Nulligravid Women

Abstract

Previous case-control studies reported more than 15 years ago found positive associations between use of an intrauterine device (IUD) and tubal infertility, and in one of them copper devices in particular were implicated.The present unmatched case-control study, undertaken at three public hospitals in Mexico City, recruited 1895 women in the years 1997-1999: 358 with primary infertility and documented tubal occlusion, 953 with primary infertility but not tubal occlusion, and 584 primigravid control women. A thorough reproductive history was taken, and blood was tested for antibodies to Chlamydia trachomatis. Risk factors were comparable in the women with tubal occlusion and the infertile control women, but compared with those with tubal occlusion, pregnant control women reported more sex partners, had lower rates of past upper genital tract infection, and described fewer symptoms of pelvic inflammatory disease. Positive tests for Chlamydia antibody also were less frequent in this group. Previous use of a copper IUD was not associated with an increased risk of tubal occlusion, regardless of which control group was included in the analysis. When pregnant control women were included, women whose partners used condoms were at half the risk as those using no contraception. Antibody to C. trachomatis in women not using a copper IUD was associated with tubal occlusion (odds ratio, 2.4) when pregnant control women were analyzed. No such effect was noted in women who had used an IUD. These findings indicate that copper IUDs are much safer than previously thought and that these devices may be considered for nulligravid women who are not at risk for sexually transmitted disease. The investigators, in fact, believe that contemporary copper IUDs may be among the most effective and safest reversible contraceptive methods and also one of the least expensive.