Re: More research

Increased menstrual bleeding, often with pain, is the most common problem of IUD use and the most common medical reason for removing IUDs. In clinical trials about 4% to 15% of women stop using IUDs for this reason within a year after insertion. Percentages are usually higher for the Lippes Loops and other unmedicated devices than for copper IUDs.
Older women and women with children generally have lower rates of removal due to bleeding and pain (332, 463). The kind of counseling and support women receive and their attitudes toward using IUDs also influence rates of discontinuation due to bleeding and pain (27). Women who want no more children, for example, may be more tolerant of heavy bleeding and less likely to discontinue than younger women who plan to have more children. Unmedicated and copper IUDs increase the volume of menstrual bleeding per cycle, probably because the IUD disturbs the blood vessels or alters the normal blood clotting mechanism in the lining of the uterus (341, 437). With unmedicated devices, blood flow increases on average by 50% to 100% above preinsertion levels (10, 132, 135, 167, 437); with copper IUDs, 20% to 50% (115, 135, 167, 207, 212, 229).

Unlike other IUDs, hormone-releasing devices decrease menstrual blood flow or, in the case of the LNG-20, may even stop menstruation altogether (amenorrhea)—an effect of the progestin hormone that they release (131, 222, 258, 308, 465, 517, 549, 562, 630). In fact, the LNG-20 has been used successfully to treat women with menorrhagia, or excessive menstrual flow (479). Hormone-releasing IUDs may increase the number of days of light bleeding and spotting. Largely because of removals due to amenorrhea, rates of removal for bleeding or pain for the LNG IUD in developing-country clinical trials were higher than for copper IUDs (517, 549). In contrast, in a European study discontinuation for bleeding and pain was less common with the LNG-20 than with the Nova-T (573) (see Table 1). With good counseling, many women recognize the benefits of decreased menstrual flow, and continuation rates are high (530). With all IUDs, abnormal bleeding and pain may be due not to the IUD itself but to pelvic inflammatory disease (PID), ectopic pregnancy, malignancy, or other conditions (45, 154). Therefore the health care provider should consider whether there is reason to suspect other conditions that might cause bleeding and pain.

Risk of anemia. An estimated 45% of nonpregnant women in developing countries are anemic by WHO's definition (460). Many more have marginal iron levels (10). Thus increased bleeding with copper and unmedicated IUDs could be a cause for concern.

IUD use has not been proved to induce clinical anemia, however. Some 1- and 2-year studies of copper and unmedicated IUDs show significant declines in levels of serum ferritin, which decrease in the early stages of iron depletion, and/or in hemoglobin, which show only in later stages (10, 115, 117, 134, 147, 167, 188, 378, 481). Others find no changes (212, 271, 284, 298, 320, 615). The few long-term studies done have found little increase in the prevalence of anemia (378, 437). In a study of the TCu-380Ag carried out in several developing countries and the US, the proportion of women with anemia rose only from 24% to 25.4% during four years of use (329). Among these women, hemoglobin levels dropped slightly during the first two years of use but then rose even higher than they had been when the women first began using the IUD (549). In a case-control study in the Dominican Republic that involved a population with a high incidence of anemia, women who had used the TCu-380Ag for three or four years were no more likely to have low serum ferritin or hematocrit than women who were not using IUDs (509). In the US and Finland studies report lower serum ferritin levels in long-term IUD users than in nonusers, but no cases of clinical anemia were seen (250, 378). Recent research suggests that women may tolerate much lower serum ferritin levels without developing clinical anemia than had been thought and that intestinal absorption of iron may increase to compensate for heavier menstrual bleeding (615). Also, in developing countries protection against repeated pregnancies—a major cause of iron depletion and anemia—may offset the increased menstrual bleeding caused by IUDs (437).

Hormone-releasing IUDs, by reducing menstrual bleeding and sometimes stopping it completely, may actually protect against anemia (479, 531, 588). The Dominican Republic study found that women who used the LNG-20 for more than three years were significantly less likely to have low serum ferritin or hematocrit than either women not using IUDs or women using unmedicated or copper IUDs (509).

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