Volume 345:561-567

August 23, 2001

Number 8

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

David Hubacher, Ph.D., Roger Lara-Ricalde, M.D., Douglas J. Taylor, Ph.D., Fernando Guerra-Infante, Ph.D., and Raymundo Guzman-Rodriguez, M.D.

ABSTRACT

Background Previous studies of intrauterine devices (IUDs), many of which are no longer in use, suggested that they might cause tubal infertility. The concern that IUDs that contain copper — currently the most commonly used type — may increase the risk of infertility in nulligravid women has limited the use of this highly effective method of birth control.

Methods We conducted a case–control study of 1895 women recruited between 1997 and 1999. We enrolled 358 women with primary infertility who had tubal occlusion documented by hysterosalpingography, as well as 953 women with primary infertility who did not have tubal occlusion (infertile controls) and 584 primigravid women (pregnant controls). We collected information on the women's past use of contraceptives, including copper IUDs, previous sexual relationships, and history of genital tract infections. Each woman's blood was tested for antibodies to Chlamydia trachomatis. We used stratified analyses and logistic regression to assess the association between the previous use of a copper IUD and tubal occlusion.

Results In analyses involving the women with tubal occlusion and the infertile controls, the odds ratio for tubal occlusion associated with the previous use of a copper IUD was 1.0 (95 percent confidence interval, 0.6 to 1.7). When the primigravid women served as the controls, the corresponding odds ratio was 0.9 (95 percent confidence interval, 0.5 to 1.6). Tubal infertility was not associated with the duration of IUD use, the reason for the removal of the IUD, or the presence or absence of gynecologic problems related to its use. The presence of antibodies to chlamydia was associated with infertility.

Conclusions The previous use of a copper IUD is not associated with an increased risk of tubal occlusion among nulligravid women, whereas infection with C. trachomatis is.

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Intrauterine devices (IUDs) have long been believed to cause pelvic inflammatory disease and subsequent tubal infertility. Many IUDs were withdrawn from the market in the United States and other countries because of concern about safety, and the use of one — the Dalkon Shield — was eventually shown to be strongly associated with pelvic inflammatory disease. Copper-containing IUDs were first approved for use in the United States in 1976 and are still being marketed. Lingering concern about the potential risks of IUDs has discouraged women — particularly those who have never been pregnant — from using even copper devices.

Research on IUDs in the 1970s and 1980s was marked by confusion and controversy. Two early reports from the Women's Health Study in the United States showed that the use of an IUD increased the risk of pelvic inflammatory disease by at least 60 percent,^1,2 although subsequent reanalyses suggested a less marked increase in risk.^3,4,5 The Oxford Family Planning Association contraceptive study^6,7 initially reported that IUD use increased the risk of pelvic inflammatory disease by a factor of 10 ; however, a refined analysis using better comparison groups and separating results according to the type of device found no significant increase in the risk of pelvic inflammatory disease with medicated devices such as copper IUDs.⁸ More recent studies by the World Health Organization⁹ and by a team of researchers in the United States¹⁰ found that the incidence of pelvic inflammatory disease among IUD users is less than 2 episodes per 1000 years of use, consistent with conservative estimates of the incidence of pelvic inflammatory disease in the general population.¹¹ A recent meta-analysis of 36 studies concluded that the use of any IUD is positively associated with pelvic inflammatory disease.¹² Good evidence suggests that the increase in the risk of pelvic inflammatory disease associated with IUD use is related only to the process of inserting the device and that after the first month of use, the risk of infection is not significantly higher than that in women without IUDs.¹³

The recognized association between pelvic inflammatory disease and tubal infertility¹⁴ has aroused some concern that the use of an IUD may lead to this complication. Two case–control studies in the United States published more than 15 years ago^15,16 reported positive associations between IUD use and tubal infertility. In subanalyses evaluating the risk according to the type of IUD used, copper devices were reported to increase the risk of tubal infertility in one study¹⁶ (though only among women with more than one sexual partner) but not in the other¹⁵; however, later reanalysis of the data in the second study suggested an increased risk of infertility associated with the copper IUD.¹⁷ Since then, numerous case–control studies^18,19,20,21 and cohort studies^22,23,24,25 have attempted to clarify the relation, but controversy has persisted.

Methods

We conducted an unmatched case–control study in three public hospitals in Mexico City, Mexico (the National Perinatology Institute, Gynecology and Obstetrics Hospital Number 4 of the Mexican Social Security Institute, and the Women's Hospital). All consecutive nulligravid, infertile women 18 years of age or older who were scheduled for diagnostic hysterosalpingography were invited to participate. Infertility was defined by the failure to conceive after one year or more of unprotected intercourse. Criteria for exclusion included previous pregnancy, tubal sterilization, and previous diagnostic laparoscopy. After undergoing hysterosalpingography, the infertile women were classified on the basis of the radiologic evidence as women with tubal occlusion (case subjects) or as infertile controls. From the same hospitals, we recruited a second control group consisting of primigravid women in their first or second trimester. In face-to-face interviews lasting an average of 20 minutes, all participants were asked about their past use of contraceptives, previous sexual relationships, and history of genital tract infections; the interviews with the infertile women were conducted before they knew whether they had tubal occlusion. The instruments for recording the results of hysterosalpingography were adapted from the recommendations of the American Fertility Society (now the American Society for Reproductive Medicine).²⁶ Participants also donated a sample of blood to be tested for antibodies to Chlamydia trachomatis. The institutional review boards of Family Health International and the participating hospitals approved the study; written informed consent was obtained from all enrolled women. Recruitment began in September 1997 and was completed in October 1999; data analysis was completed in December 2000.

We recruited 1311 infertile women (358 women with tubal occlusion and 953 controls) and 584 pregnant controls; fewer than 5 percent of the women who met the eligibility criteria declined to participate. We designed the study to have 90 percent power to detect a doubling of the risk of tubal occlusion with IUD use in analyses involving the infertile controls; the study had 87 percent power to detect a doubling of the risk in analyses involving the pregnant controls (two-sided test, 0.05 alpha level).²⁷ If we set the power at the standard 80 percent level, we had enough study subjects to detect odds ratios of 1.8 and 1.9 in analyses involving the infertile controls and the pregnant controls, respectively.

Before recruitment began, the radiologists met to standardize their approach to classifying tubal pathology. Tubal occlusion was diagnosed if a water-based contrast medium failed to spill from either tube into the peritoneal cavity. Fluoroscopy was used, and the last films were taken 15 minutes after the contrast medium had been injected. The radiologists were unaware of the information collected in the women's interviews.

Serologic tests for detecting antibodies to chlamydia are accepted measures of past infection.^28,29,30 An indirect fluorescent IgG antibody–staining kit (Hemagen Diagnostics, Columbia, Md.) was used to process the serum samples. As in previous studies using these kits, samples that tested positive at dilutions of 1:256 were considered diagnostic of past exposure to C. trachomatis.³¹ All serum samples were processed as recommended by the manufacturer.

Our primary exposure variable was the previous use or nonuse of an IUD containing copper. Other variables that were considered as possibly predictive of tubal infertility included the presence or absence of antibodies to C. trachomatis, the number of lifetime sexual partners, the presence or absence of a history of genital tract infections, the presence or absence of a history of gynecologic symptoms suggestive of infection, the past use or nonuse of other methods of contraception, family income, education, employment status, and the presence or absence of a history of coitus during the teenage years. Regarding their most recent sexual partners (up to six), the women were asked about the length of the relationship and whether they believed their partners had engaged in concurrent sexual relations with other women. To adjust for age, we used the age when the infertile women first suspected they were unable to conceive and the age when the pregnant women first began attempting to conceive. We excluded from the analyses exposure that occurred after the onset of infertility.

We classified women into one of six mutually exclusive groups on the basis of use of contraceptive methods: no previous method (or rhythm or withdrawal), condoms only, vaginal spermicides only, hormonal methods only (oral or injectable contraceptives), condoms and hormonal methods, and IUDs (none of the women reported a history of diaphragm use). If a previous user of vaginal spermicides had also used one of the other methods, she was assigned to the group that used that other method. All women who had used an IUD reported having used a device containing copper. The vast majority of the copper IUDs used by the women in the study were T-shaped (containing either 220 mm² or 380 mm² of copper surface). Data were collected on the duration of use of a given method, any gynecologic problems that occurred during its use, and the reasons for the discontinuation of its use.

We calculated crude and adjusted odds ratios (with 95 percent confidence intervals) as measures of the association between IUD use and tubal occlusion. Logistic regression was used to control for other factors simultaneously.

Results

The infertile women with tubal occlusion (case subjects) and the infertile controls were similar in terms of level of education, employment status, family income, and number of months spent attempting to conceive (Table 1). As compared with the women with tubal occlusion, the pregnant controls were younger, better educated, and less likely to work outside the home and had lower family incomes.

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Table 1. Selected Characteristics of the Infertile and Pregnant Women.

The prevalence of the possible risk factors for tubal occlusion was similar among the women with tubal occlusion and the infertile controls (Table 2). However, as compared with the women with tubal occlusion, the pregnant controls had had more sexual partners, were more likely to report suspected infidelity by partners, and had lower rates of previous upper genital tract infection, symptoms of pelvic inflammatory disease, and positive tests for antibodies to chlamydia.

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Table 2. Possible Risk Factors for Tubal Occlusion.

When no previous contraceptive use was defined as the reference category, previous use of a copper IUD was not associated with an increased risk of tubal occlusion either in the analysis including the infertile controls (odds ratio, 1.0; 95 percent confidence interval, 0.6 to 1.6) or in the analysis including the pregnant controls (odds ratio, 0.7; 95 percent confidence interval, 0.4 to 1.2) (Table 3). In the latter analysis, women whose sexual partners used condoms had a 50 percent lower risk of tubal occlusion than those who used no contraception.

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Table 3. Previous Use of Contraceptives and the Risk of Tubal Occlusion.

Similarly, when no previous IUD use was defined as the reference category, previous use of a copper IUD was not associated with tubal occlusion in the analyses including either the infertile controls (odds ratio, 1.0; 95 percent confidence interval, 0.6 to 1.7) or the pregnant controls (odds ratio, 0.9; 95 percent confidence interval, 0.5 to 1.6) (Table 4). A longer duration of use of a copper IUD, the removal of the IUD because of side effects, and a history of gynecologic symptoms during the use of a copper IUD were not associated with increased odds of tubal occlusion.

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Table 4. History of Use of a Copper IUD and the Risk of Tubal Occlusion.

The presence of antibodies to C. trachomatis among women who had not used a copper IUD was associated with tubal occlusion (odds ratio, 2.4; 95 percent confidence interval, 1.7 to 3.2) in the analysis including the pregnant controls (Table 5). Among women who had used an IUD, there was no significant association between antibodies to C. trachomatis and tubal infertility, but there were relatively few women in this group.

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Table 5. Use of a Copper IUD, the Presence of Antibodies to Chlamydia trachomatis, and the Risk of Tubal Occlusion.

We considered using a broader definition of a case to include either tubal occlusion or adhesions, but hysterosalpingography has a limited ability to identify adhesions.^32,33 To address the concern that our case group was defined too narrowly because we excluded women who had adhesions only, we performed an additional analysis. This analysis involved reclassifying as case subjects the infertile controls who had no occlusion but had adhesions identified on hysterosalpingography and positive serologic tests for C. trachomatis. Previous research suggests that serologic testing for chlamydia may improve the accuracy of the diagnosis of tubal disease when used in conjunction with, or even in place of, hysterosalpingography.^34,35 After this reclassification, the adjusted odds ratios for tubal infertility associated with IUD use were 1.2 (95 percent confidence interval, 0.7 to 1.9) for the analysis including the infertile controls and 1.0 (95 percent confidence interval, 0.6 to 1.5) for that including the pregnant controls.

Although hysterosalpingography is the standard method for evaluating tubal patency,³⁶ it has some diagnostic limitations that laparoscopy does not have. Of the 1311 infertile women in our study, only 321 (24 percent) underwent laparoscopy. Those with abnormal results on hysterosalpingography were twice as likely as women with negative results to undergo laparoscopy. Using the laparoscopy reports, we divided this subgroup into 185 women with any evidence of tubal disease, including adhesions, and 136 infertile controls with no evidence of tubal disease. The adjusted odds ratio for tubal infertility associated with previous IUD use was 1.5 (95 percent confidence interval, 0.7 to 3.5) in analyses including the infertile controls and 1.9 (95 percent confidence interval, 1.0 to 3.5) in analyses using the pregnant controls.

Discussion

Our finding that the use of a copper IUD was not a risk factor for tubal occlusion among nulligravid women contradicts some previous reports that aroused concern about future fertility in women who use copper IUDs.^15,16 Given the media attention to the problems with the Dalkon Shield and the associated litigation in U.S. courts during the 1970s and 1980s, women who were infertile and had previously used an IUD may have been more inclined to investigate the cause of their condition than infertile women who had never used an IUD. Consequently, women with a history of IUD use may have been disproportionately represented in previous studies in the United States of women with tubal infertility. In contrast, our study was conducted in Mexico, where IUD use is well accepted and where such bias is unlikely to occur.

Past research on this topic used only primigravid women as controls. We included an infertile control group for several reasons. First, we wanted to ensure that the women with tubal occlusion came from the same population as the controls. Second, this approach minimizes bias due to the differential recall of IUD use according to diagnosis. We also included a control group of pregnant women to address the association between IUD use and the inability to conceive.

Exposure to C. trachomatis has been cited as an important cause of tubal infertility.^21,37 We found higher rates of positive tests for antibodies to chlamydia, a validated marker of past exposure,^28,29,30 among women with tubal occlusion and among infertile controls than among pregnant women. A weakness of the antibody test is that it does not indicate whether exposure to C. trachomatis preceded the onset of tubal disease, although it is likely that it did. The fact that the prevalence of antibodies was similar among women with tubal occlusion and infertile controls is not surprising, since the infertile controls may have had other evidence of disease attributable to chlamydia, such as adhesions, which are not readily detectable by hysterosalpingography.^32,33 Thus, it is possible that previous studies found an increased risk of tubal infertility associated with the use of a copper IUD because of the unmeasured confounding effect of exposure to sexually transmitted disease — specifically, C. trachomatis.

Laparoscopy is another diagnostic procedure for women with infertility. The decision about whether to undergo laparoscopy is an individual one that depends on clinical findings (including those from hysterosalpingography) and other factors, such as the presence or absence of a history of pelvic pain. In our study, only one quarter of the women underwent laparoscopy, including a disproportionate number of those with abnormal results on hysterosalpingography. The adjusted odds ratios for tubal infertility according to the analysis of the women who underwent laparoscopy, although higher than those calculated on the basis of all the women who underwent hysterosalpingography, were not inconsistent with the results of the primary analysis, and the differences between these ratios may reflect selection bias. An unbiased study in which laparoscopy was required for the identification of cases would not be feasible because of its cost, the time it would consume, and the ethical problems it would raise. Our analysis, based on hysterosalpingographic results, focused on damage to the lumen of the fallopian tubes; it is unlikely that we found no increased risk associated with IUD use simply because copper IUDs affect only structures exterior to the fallopian tubes.

More than 100 million women worldwide use IUDs. Asia accounts for the majority of use, but IUD use is also common among married women of reproductive age in Scandinavian countries (prevalence, 18 percent) and in other European countries (7 percent).³⁸ In contrast, only 1 percent of women in the United States use the IUD.³⁹ This low rate is thought to reflect the widespread concern about health risks associated with the method. In lieu of using an IUD, women may prematurely request sterilization (and may regret it later^40,41), choose less effective or less convenient methods, or risk an unwanted pregnancy.

This study suggests that the use of copper IUDs is much safer than was previously thought. Nulligravid women who are not at risk for a sexually transmitted disease are appropriate candidates for the copper IUD. Contemporary copper IUDs may be among the safest, most effective, and least expensive reversible contraceptives available.^42,43

Supported by the U.S. Agency for International Development (USAID) through a contract with Family Health International (contract CCP-A-00-95-00022-02) and by the National Institute for Child Health and Human Development, National Institutes of Health, through an Interagency Agreement (Y1-HD-7230-01) with USAID. This article does not necessarily reflect the views or policies of the Department of Health and Human Services or of USAID, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. government.

We are indebted to the participants for making this research possible and to Rocío Dávila-Mendoza, Dr. Zigor Campos-Goenaga, Dr. Maria del Carmen Tavera-Hernández, Maria Elena Guevara-Reyes, Enimia Zárate-Aragón, Bersabe Bautista-García, Deborah Cousins, Dr. Jaroslav Hulka, Cathy Dudnanski, Carmen Cardenas-Lopez, Dr. David Grimes, Dr. Ken Schulz, Dr. Julio de la Jara, Dr. Esteben Garcia, Dr. Alonso Garcia-Luna, Marie McLeod, and Research Triangle Institute.

Source Information

From Family Health International, Research Triangle Park, N.C. (D.H., D.J.T.); and the National Perinatology Institute, Mexico City, Mexico (R.L.-R., F.G.-I., R.G.-R.).

Address reprint requests to Dr. Hubacher at Family Health International, P.O. Box 13950, Research Triangle Park, NC 27709, or at [log in to unmask].

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17. Daling JR, Weiss NS, Voigt LF, McKnight B, Moore DE. The intrauterine device and primary tubal infertility. N Engl J Med 1992;326:203-204.[Medline]

18. Brabin L, Gogate A, Gogate S, et al. Reproductive tract infections, gynaecological morbidity and HIV seroprevalence among women in Mumbai, India. Bull World Health Organ 1998;76:277-287.[Medline]

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20. Lalos O. Risk factors for tubal infertility among infertile and fertile women. Eur J Obstet Gynecol Reprod Biol 1988;29:129-136.[Medline]

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22. Wilson JC. A prospective New Zealand study of fertility after removal of copper intrauterine contraceptive devices for conception and because of complications: a four-year study. Am J Obstet Gynecol 1989;160:391-396.[Medline]

23. Doll H, Vessey M, Painter R. Return of fertility in nulliparous women after discontinuation of the intrauterine device: comparison with women discontinuing other methods of contraception. BJOG 2001;108:304-314.[Medline]

24. Skjeldestad F, Bratt H. Fertility after complicated and non-complicated use of IUDs: a controlled prospective study. Adv Contracept 1988;4:179-184.[Medline]

25. Anwar M, Widayanto S, Maruo T, Mochizuki M. Return of fertility after the removal of intrauterine devices: a comparison of inert and copper bearing devices. Asia Oceania J Obstet Gynaecol 1993;19:77-83.[Medline]

26. The American Fertility Society classifications of adnexal adhesions, distal tubal occlusion, tubal occlusion secondary to tubal ligation, tubal pregnancies, mullerian anomalies and intrauterine adhesions. Fertil Steril 1988;49:944-955.[Medline]

27. Schlesselman JJ. Case control studies: design, conduct, analysis. New York: Oxford University Press, 1982.

28. Tuuminen T, Palomaki P, Paavonen J. The use of serologic tests for the diagnosis of chlamydial infections. J Microbiol Methods 2000;42:265-279.[Medline]

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32. Karande VC, Pratt DE, Rabin DS, Gleicher N. The limited value of hysterosalpingography in assessing tubal status and fertility potential. Fertil Steril 1995;63:1167-1171.[Medline]

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34. Thomas K, Coughlin L, Mannion PT, Haddad NG. The value of Chlamydia trachomatis antibody testing as part of routine infertility investigations. Hum Reprod 2000;15:1079-1082.[Abstract/Full Text]

35. Dabekausen YA, Evers JL, Land JA, Stals FS. Chlamydia trachomatis antibody testing is more accurate than hysterosalpingography in predicting tubal factor infertility. Fertil Steril 1994;61:833-837.[Medline]

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Volume 345:608-610

August 23, 2001

Number 8

Time to Pardon the IUD?

The report in this issue of the Journal on the effect of copper intrauterine contraceptive devices on the risk of infertility in nulliparous women deserves the attention of American women and their clinicians.¹ Despite the efficacy of the intrauterine device (IUD) in preventing pregnancy, concern that the use of an IUD may cause pelvic infection and infertility has made it a contraceptive option that is rarely used in the United States.

Hubacher et al. report the results of a case–control study involving nearly 2000 women in Mexico City, Mexico.¹ The study compared nulligravid infertile women who had tubal occlusion with infertile women who did not have tubal occlusion, as well as with pregnant women, in terms of the previous use of IUDs and other potential risk factors for infertility. They also tested the women for the presence of antibodies to Chlamydia trachomatis, the most important contributor to infertility. The authors found no increase in the risk of tubal occlusion associated with the previous use of copper IUDs; in analyses involving the infertile controls, the odds ratio associated with the use of a copper IUD was 1.0 (95 percent confidence interval, 0.6 to 1.7), and similar results were found in analyses involving the pregnant controls. By contrast, there was a strong association between previous chlamydial infection and infertility in these women. This important study could not have been conducted in the United States, because nulliparous women rarely use intrauterine contraception here, and even women in this country who have already borne a child have tended to shun these devices, but the results should change current opinion about copper IUDs.

The use of intrauterine contraception has declined in the United States even as it has increased in the rest of the world. Thirty years ago, nearly 10 percent of women in the United States who used contraception chose IUDs, but now less than 1 percent do so. In contrast, more than one in five women in Denmark and Germany use IUDs. Reluctance to use IUDs and other highly effective methods of contraception is one reason why, by the end of their childbearing years, nearly half of the women in the United States (46 percent) have had at least one elective abortion, and 27 percent have undergone surgery for sterilization. These rates are about three times as high as those in western Europe.

It is ironic that the modern IUD, now largely rejected here, was developed by gynecologists in the United States, and its use was a routine part of gynecologic practice in this country 30 years ago. What changed? Research to create IUDs that caused less menstrual pain and bleeding, the principal reasons why women had the devices removed, led to the development of the infamous Dalkon Shield, a poorly designed and poorly tested device designed to accommodate nulliparous women. Introduced just at the time the danger of venous thrombosis associated with oral contraceptives was becoming widely publicized, the Dalkon Shield appealed to sexually active young women.

I and many other gynecologists inserted the new Dalkon Shield, with its spiny margins and braided tail, in our young patients because we thought it would be better tolerated than earlier IUDs by a uterus that had never sustained a pregnancy and because we had been deceived about its efficacy.² We did not worry about health risks because IUDs were considered safe on the basis of early research.^3,4 The Food and Drug Administration (FDA) was not yet responsible for evaluating the safety of such devices in clinical trials.

Our complacency was disturbed in 1973 when the Family Planning Evaluation Division at the Centers for Disease Control reported several deaths due to pelvic infection related to the use of IUDs.^5,6 Subsequent retrospective case–control studies linked IUDs with sexually transmitted infections, which had become a major cause of infertility.^7,8 Further research found a direct relation between IUD use and infertility due to tubal occlusion.^9,10 These reports formed the foundation for litigation, first against the sellers of the Dalkon Shield and then against other companies that manufactured IUDs. Although the FDA forced only the Dalkon Shield from the market, the other U.S. manufacturers abandoned sales in order to avoid legal costs. As a result, no IUDs were sold in the United States between 1983 and 1988, and many women, frightened by reports of infection and infertility, had their IUDs removed. Soon, teaching about contraception condemned IUDs, and the few physicians who still trusted intrauterine contraception had neither devices to insert nor patients who wanted them.

In the rest of the world, however, intrauterine contraceptive devices continued to be used, and ongoing research resulted in better devices. One, the copper T 380 (with 380 mm² of copper surface), was introduced to an empty U.S. market in 1988 by a company too small to attract litigation or, initially, many customers. This device (which goes under the trade name ParaGard) is the only copper IUD available in the United States but is one of several used in Mexico and other countries. Although few IUDs were provided to women in the United States during the past 20 years, reanalyses of previously collected data and new retrospective case–control studies have helped to identify the characteristics of IUDs and their users that were associated with pelvic infection and infertility.¹¹ The use of the Dalkon Shield was associated with a much higher relative risk of pelvic infection than any of the others (eight times as high), indicating that its inclusion in previous studies had inflated the risk associated with IUDs in general.¹² Other results demonstrated that women in relationships that were more likely to be exclusive (marriage or cohabitation) were not at increased risk,¹³ supporting the contention that "men, not IUDs," cause pelvic infection.

Because pelvic infection can occlude the oviducts and cause infertility, epidemiologists in Seattle and Boston examined the relation between previous IUD use and subsequent tubal infertility.^9,10 It is with these two case–control studies, published in the Journal 16 years ago, that the report in this week's issue of the Journal should be compared. Neither found a significantly increased risk of tubal infertility associated with the use of a copper IUD (relative risk, 1.5 [95 percent confidence interval, 0.8 to 3.0] and 1.3 [95 percent confidence interval, 0.6 to 3.0], respectively), and both determined that IUDs made of plastic did increase the risk. Although the 95 percent confidence intervals span 1.0 (indicating no increased risk), the point estimates were used to indict copper IUDs along with all other types.

The finding of the present study that exposure to chlamydia is associated with infertility provides an explanation for previous reports of an increased risk of pelvic infection among women who were not involved in exclusive relationships and an increased risk associated with the insertion, but not the prolonged use, of IUDs.¹⁴ At the time of these earlier studies,^9,10 C. trachomatis was not recognized as an important cause of tubal infertility.

No matter what form of contraception a woman chooses, the increasing prevalence of chlamydia and other sexually transmitted pathogens, including the human immunodeficiency virus, means that condoms should be used with high-risk partners. But the findings reported by Hubacher et al. should reassure clinicians and women alike that copper IUDs, which are by far the most common type of IUD used in the United States and around the world, are not a threat to the health or future fertility of the women who use them, including those without children.

Philip D. Darney, M.D.
University of California, San Francisco
San Francisco, CA 94110

References

1. Hubacher D, Lara-Ricalde R, Taylor DJ, Guerra-Infante F, Guzmán-Rodríguez R. Use of copper intrauterine devices and the risk of tubal infertility among nulligravid women. N Engl J Med 2001;345:561-567.[Abstract/Full Text]

2. Tatum HJ, Schmidt FH, Phillips D, McCarty M, O'Leary WM. The Dalkon Shield controversy: structural and bacteriological studies of IUD tails. JAMA 1975;231:711-717.[Medline]

3. Mishell DR Jr, Bell JH, Good RG, Moyer DL. The intrauterine device: a bacteriologic study of the endometrial cavity. Am J Obstet Gynecol 1966;96:119-126.[Medline]

4. Tietze C. Evaluation of intrauterine devices: ninth progress report of the Cooperative Statistical Program. Stud Fam Plann 1970;1:1-40.

5. Christian CD. Maternal deaths associated with an intrauterine device. Am J Obstet Gynecol 1974;119:441-444.[Medline]

6. Taylor ES, McMillan JH, Greer BE, Droegemueller W, Thompson HE. The intrauterine device and tubo-ovarian abscess. Am J Obstet Gynecol 1975;123:338-348.[Medline]

7. Eschenbach DA, Harnisch JP, Holmes KK. Pathogenesis of acute pelvic inflammatory disease: role of contraception and other risk factors. Am J Obstet Gynecol 1977;128:838-850.[Medline]

8. Kaufman DW, Shapiro S, Rosenberg L, et al. Intrauterine contraceptive device use and pelvic inflammatory disease. Am J Obstet Gynecol 1980;136:159-162.[Medline]

9. Daling JR, Weiss NS, Metch BJ, et al. Primary tubal infertility in relation to the use of an intrauterine device. N Engl J Med 1985;312:937-941.[Abstract]

10. Cramer DW, Schiff I, Schoenbaum SC. Tubal infertility and the intrauterine device. N Engl J Med 1985;312:941-947.[Abstract]

11. Kronmal RA, Whitney CW, Mumford SD. The intrauterine device and pelvic inflammatory disease: the Women's Health Study reanalyzed. J Clin Epidemiol 1991;44:109-122.[Medline]

12. Lee NC, Rubin GL, Ory HW, Burkman RT. Type of intrauterine device and the risk of pelvic inflammatory disease. Obstet Gynecol 1983;62:1-6.[Medline]

13. Lee NC, Rubin GL, Borucki R. The intrauterine device and pelvic inflammatory disease revisited: new results from the Women's Health Study. Obstet Gynecol 1988;72:1-6.[Medline]

14. Farley TMM, Rosenberg MJ, Rowe PJ, Chen J-H, Meirik O. Intrauterine devices and pelvic inflammatory disease: an international perspective. Lancet 1992;339:785-788.[Medline]

Edward E. Rylander, M.D.

Diplomat American Board of Family Practice.

Diplomat American Board of Palliative Medicine.