Dose- and age-dependent ectopic pregnancy risks with intrauterine contraception.
Analyses of randomized trials of copper intrauterine devices (IUDs) substantiate three hypotheses: 1) Ratios of ectopic to total pregnancies conceived during copper IUD use did not differ among devices; 2) pregnancy rates per 1000 woman-years varied inversely with copper surface area; and 3) ectopic pregnancy rates consequently varied inversely by copper surface area. Randomized trials also demonstrated that progestin-only IUDs had a markedly higher ratio of ectopic to total pregnancies, 171 per 1000, than did copper IUDs, at 39 per 1000 (P less than .001). Ectopic pregnancy rates per 1000 woman-years with progestin-only IUDs varied inversely with dose, notably for levonorgestrel-releasing devices. In a large United States IUD cohort study, ectopic pregnancy ratios of copper IUDs varied significantly (P less than .05) with age, as they do in the general population. Copper and non-medicated IUDs in the United States and the United Kingdom had age-specific ectopic pregnancy ratios six times those of non-contraceptors in the United States population during 1970-1978. The estimated rate of ectopic pregnancy for users of IUDs having 200 mm2 of copper was four-tenths that of non-contraceptors in the United States during 1970-1978. For users of devices with 350 mm2 or more of copper, ectopic pregnancy rates were one-tenth those of non-contraceptors. Rates for users of devices releasing 65 micrograms/day of progesterone are estimated to have been 50-80% above those of non-contraceptors. Devices releasing 20 micrograms/day of levonorgestrel have had ectopic pregnancy rates estimated to be 0.1 of those of non-contraceptors. Most IUDs protect against ectopic pregnancy.
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Center for Biomedical Research, Population Council, New York, New York.
D000367:Age Factors; D005260:Female; D006801:Humans; D007434:Intrauterine Devices; D007435:Intrauterine Devices, Copper; D007436:Intrauterine Devices, Medicated; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000453:epidemiology / Q000209:etiology*; D011372:Progestins / Q000008:administration & dosage; D012307:Risk Factors
D011372:Progestins