Hum. Reprod. Advance Access originally published online on December 22, 2005
Human Reproduction 2006 21(5):1316-1319; doi:10.1093/humrep/dei457
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A cross-sectional study of the forearm bone density of long-term users of levonorgestrel-releasing intrauterine system
Human Reproduction Unit, Department of Obstetrics and Gynaecology, School of Medicine, Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
1 To whom correspondence should be addressed at: Caixa Postal 6181, 13084–971, Campinas, SP, Brazil. E-mail: bahamond{at}caism.unicamp.br
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Abstract |
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BACKGROUND: There are concerns about the effect of hormonal contraceptives on bone mineral density (BMD), but there is currently no information available on the effect of the levonorgestrel-releasing intrauterine system (LNG-IUS) on BMD. The objective of this study was to compare the BMD of LNG-IUS users with that of controls using the TCu380A intrauterine device (IUD). MATERIALS AND METHODS: A cross-sectional study paired 53 women, aged 25–51 years, who had been using the LNG-IUS for 7 years, with 53 IUD users, according to age (±1 year) and body mass index (BMI; kg/m2) (±1). BMD was evaluated at the midshaft of the ulna and the distal radius of the nondominant forearm using double X-ray absorptiometry. RESULTS: Mean age of women was 34 years. BMI was slightly over 25 in both groups. Estradiol was normal. Mean BMD was 0.469 ± 0.008 and 0.467 ± 0.009 and 0.409 ± 0.009 and 0.411 ± 0.009 at the midshaft of the ulna and distal radius in LNG-IUS and IUD users, respectively, without significant differences. CONCLUSIONS: Women aged 25–51 years, using the LNG-IUS for 7 years, had a mean BMD similar to that of the control group of TCu380A IUD users.
Key words: bone mineral density/contraception/levonorgestrel-releasing intrauterine system/Mirena®
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Introduction |
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If we consider that a woman initiates her sexual life at 16 years of age, undergoes menopause at 50, and has two children who are breastfed exclusively for 6 months each, then women require contraception for around 30–32 years of their life. Many women, therefore, require contraceptive methods that offer long-term protection. The levonorgestrel-releasing intrauterine system (LNG-IUS) has been approved for a 5-year term of use in more than 100 countries and provides high contraceptive efficacy with few adverse effects (Luukkainen et al., 1990
; World Health Organization, 2004).
One of the effects of the use of the LNG-IUS is amenorrhoea provoked by the antiproliferative effect of LNG on the endometrium (Luukkainen et al., 1990; Ronnerdag and Odlind, 1999; Hidalgo et al., 2002). This is one of the non-contraceptive benefits of the LNG-IUS and permits its use in menorrhagic patients as an alternative to hysterectomy (Monteiro et al., 2002; Hurskainen et al., 2004) and in women suffering from endometriosis-related pain (Lockhat et al., 2005; Petta et al., 2005). However, despite the amount of information regarding the contraceptive effect and the health benefits of the use of the LNG-IUS, we have been unable to find any study that evaluated the bone mineral density (BMD) of users of this contraceptive method.
Progestogen-only (p-only) contraceptive methods are in use worldwide, and the effect of current and past use on BMD is a medical concern (World Health Organization, 2005), mainly with respect to users of the injectable depot-medroxyprogesterone acetate (DMPA) (Kaunitz, 2005; United States Food and Drug Administration, 2004), since this method provokes transient but profound hypo-estrogenism (Bahamondes et al., 2000) that it is one of the most important factors related to bone loss (Bagger et al., 2004), particularly in amenorrhoeic women. However, even in DMPA users, the effect on BMD is controversial with some studies showing a deleterious effect (Cundy et al., 1991, 1998; Gbolade et al., 1998; Petitti et al., 2000), while others report no effect whatsoever (Bahamondes et al., 1999; Perrotti et al., 2001).
Although amenorrhoea is common in users of the LNG-IUS (Ronnerdag and Odlind, 1999; Hidalgo et al., 2002), ovulatory cycles are quite common in most users (Barbosa et al., 1995). In addition, estradiol (E2) plasma levels are similar to those found during the follicular phase of the menstrual cycle (Nilsson et al., 1984; Luukkainen et al., 1990) or higher in the case of persistent ovarian follicles (Bahamondes et al., 2003). Since serum levels of E2 are normal, use of the LNG-IUS is not expected to affect BMD; however, no studies have yet been carried out to confirm this hypothesis. The objectives of this study were, therefore, to evaluate the BMD of long-term users of the LNG-IUS and compare them with users of non-hormonal contraceptive methods as controls.
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Materials and methods |
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The study was conducted at the Human Reproduction Unit, Department of Obstetrics and Gynecology, School of Medicine, Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil. The Ethical Committee of the institution approved the study, and all participants signed an informed consent form prior to admission.
The subjects were a sub-sample of a larger group of women participating in an acceptability study of the LNG-IUS (Mirena®, Schering Oy, Turku, Finland) in Brazil, who had their devices inserted between April and September, 1998 (Diaz et al., 2000; Hidalgo et al., 2002). At the end of the approved 5-year lifespan of the device, the women were invited to retain the same device for a further 2 years. At the 7-year follow-up visit, the first 56 women who returned for a control evaluation were invited to participate in this study. Those who accepted were submitted to the study procedures. Three women with body mass index (BMI, kg/m2) >40 were excluded because a paired control could not be found for them. Therefore, 53 women aged 25–51 years of age were evaluated. The control group was composed of 53 women who had been users of the TCu380A intrauterine device (IUD) for at least the same 7 years, and who were paired with the users of the LNG-IUS by age (±1 year) and BMI (kg/m2) (±1).
Women were excluded if they were using calcium, vitamin D, anticonvulsants, corticosteroids, thiazide diuretics or drugs for the treatment of thyroid disease. Women with chronic diseases such as diabetes mellitus, chronic renal failure, hyperthyroidism or hypothyroidism, hyperparathyroidism or hypoparathyroidism, hepatitis, cancer or pituitary diseases were also excluded.
Definition of variables
BMD was the dependent variable and was defined as the relationship between bone mineral content (g/cm2) and the area of the bone measured. The independent variable was the use of the LNG-IUS or IUD. The control variables included age at time of the BMD measurement, ethnicity, number of pregnancies and deliveries, time of exclusive and partial breast-feeding, weight, height, BMI (kg/m2), duration of exercise practice, smoking habits and patterns of coffee and alcohol consumption.
Bone mineral density measurement
BMD was measured at the nondominant forearm using double X-ray absorptiometry (DXA) (DTX-200; Osteometer Meditech A/S, Rodovre, Denmark). The normal mean value in premenopausal women is 0.481 g/cm2. Two measurements of BMD were taken in each woman: (1) at the midshaft of the ulna (where cortical bone predominates), where the radius is 8 mm from the ulna, and (2) at the distal radius near the articulation with the bones of the carpus (where trabecular bone predominates).
Estradiol measurement
Before performing the evaluation of BMD, a blood sample was taken from a peripheral vein. After coagulation, the serum was separated and frozen at –20°C until being measurement of assayed. E2 levels were measured by electrochemiluminescence immunoassay (ECLIA) using a commercial kit (Roche Diagnostics GmbH, Mannheim, Germany) with a measuring range of 5.0–4300 pg/ml and interassay coefficient of variation of 4.9%. All samples were measured in duplicate.
Statistical analysis
Due to the lack of information on the BMD of users of the LNG-IUS, it was impossible to estimate sample size, and for this reason, a pilot study was carried out with 53 women in each group. The comparison of demographic, anthropometric and obstetric variables and the BMD at both sections of the forearm, between the two groups of users, was performed using Student’s t-test for matched samples, Wilcoxon signed rank test or Chi-square test when appropriate (Armitage, 1971). All data are presented as mean ± standard error of the mean (SEM).
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Results |
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Table I shows selected sociodemographic and obstetric characteristics of the two study groups. The mean age of LNG-IUS and IUD users at the time of BMD measurement was 34.2 ± 0.9 and 34.6 ± 0.9 years, respectively. The BMI (kg/m2) at the time of evaluation was 25.8 ± 0.5 and 25.5 ± 0.5 in the two groups of users, respectively, and there was no statistically significant difference between the two groups either for this variable or for any of the other characteristics. White women comprised 86 and 72%, while smokers made up 11 and 26% (P < 0.047) of users of the LNG-IUS and IUD, respectively. All women in the study group had been using the LNG-IUS for 7 years, while women in the control group had been using the TCu380A IUD for a mean of 9.7 ± 2.0 years (range 7–17 years).
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Twenty-eight out of 53 women were amenorrheic, and the remaining 25 presented only a few episodes of spotting. E2 level in Mirena® users measured at the same time at which BMD was evaluated was 98.2 ± 12.7 pg/ml. The BMD at the midshaft of the ulna was 0.469 ± 0.008 and 0.467 ± 0.009 and at the distal radius was 0.409 ± 0.009 and 0.411 ± 0.009 in LNG-IUS and IUD users, respectively. There were no statistically significant differences between the two groups (Table II). When the women were divided into two groups under 35 years old or 
35 years old, there were no significant differences between BMD at both section of the forearm or between users of both contraceptive methods (Table III).
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Discussion |
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The results of our study show that long-term users of the LNG-IUS, at 7 years of use, had similar BMD at the midshaft of the ulna and at the distal radius as nonusers matched by age and BMI (kg/m2). In addition, BMD measurements were similar to the expected values for women in the same age group as the participants (Z-score) (World Health Organization, 1994
).
It is well established that the main factor responsible for bone loss in women is hypo-estrogenism (Bagger et al., 2004). Since E2 levels found in our study group were similar to those found during the follicular phase of the normal menstrual cycle, our results were predictable and are in agreement with previous reports showing values ranging from 100 to 400 pg/ml from insertion through 7 years of use (Nilsson et al., 1984; Luukkainen et al., 1990; Barbosa et al., 1995; Bahamondes et al., 2003). However, since amenorrhoea is a common bleeding pattern during use of the LNG-IUS (Ronnerdag and Odlind, 1999), affecting almost 60% of users at our centre at the end of the first year of use (Hidalgo et al., 2002), it may pose a concern to users and physicians with respect to the potential risk to the bone health of these women.
No decrease was expected in the BMD of users of contraceptives containing LNG, since this steroid, as a 19 nor-progestogen, is considered to have a beneficial effect on BMD (Petitti et al., 2000), and it was postulated that at contraceptive doses LNG could inhibit bone absorption in women of reproductive age (Volpe et al., 1997). Several studies evaluating BMD in users of the LNG-releasing contraceptive implants (Norplant® or Jadelle®) reported no significant adverse effects on BMD at the lumbar spine (L2–L4), femoral neck or distal radius where trabecular bone is predominant (Naessen et al., 1995; Petitti et al., 2000; Bahamondes et al., in press). In addition, an increment was observed in the BMD of adolescents (Cromer et al., 1996) and adults at 12 months of exposure (Diaz et al., 1999). These results are in agreement with the findings of the present study at both sections of the forearm.
The Norplant® implant releases LNG during the first year of use at a rate of almost 100 µg/day and decreases to a fairly constant rate that is close to 30 µg/day in the second and subsequent years up to year 6 of use (Robertson et al., 1983; Diaz et al., 1982, 1987). In comparison, the LNG-IUS releases an intrauterine dose of 20 µg/day at insertion and almost 12 µg/day at 7 years of use (Luukkainen et al., 1990). Although the intrauterine levels of LNG were significantly higher than the blood levels of users (Nilsson et al., 1982), there was no evidence that these low LNG serum levels had any influence on BMD.
In LNG-IUS users of reproductive age, serum LNG concentrations reach a plateau of 0.15–0.20 µg/ml after the first few weeks post-insertion, undergoing a decline over 5 years (Luukkainen et al., 1990); however, in Norplant® users, these blood levels remain almost double (0.3–0.4 µg/ml) through 8 years of use (Diaz et al., 1987). LNG binds to sex hormone-binding globulin (SHBG) and albumin, with only 1–2% of the total serum LNG levels representing the free steroid. Furthermore, serum LNG levels in Mirena® users correlate with SHBG levels, and serum SHBG levels do not change significantly following insertion of the LNG-IUS (Luukkainen et al., 1990; Jia et al., 1992).
In addition, the LNG-IUS is registered in more than 80 countries for use as endometrial protection in women using estrogen therapy (ET) in the peri- and postmenopause (Raudaskoski et al., 1995, 2002; Hampton et al., 2005). Consequently, the effect of LNG on BMD is crucial, especially in these women because ET induces SHBG and could affect serum LNG levels. Oral estrogen has a marked SHBG-inducing effect, whereas transdermal estrogen has virtually no effect (Chetkowski et al., 1986). In users of Mirena® as endometrial protection during ET in the postmenopause, plasma LNG levels range from 0.20 µg/ml (Raudaskoski et al., 1995) to 0.48 µg/ml (Raudaskoski et al., 2002). Therefore, the large variation in LNG concentration found in postmenopausal women using Mirena®, and ET could be attributable to SHBG induction.
Although this is the first report on the effect of Mirena® on BMD, we recognize that new studies need to be carried out on a larger number of cases and in different ethnic groups, to measure BMD at other sites of the skeleton (Marshall et al., 1996). In addition, prospective studies to evaluate the risk of fracture and studies of women of various age groups including postmenopausal women are required. However, despite these limitations, it is possible to conclude that long-term users of the LNG-IUS presented similar BMD at midshaft of the ulna and at the distal radius when compared to non-users paired by age and BMI (kg/m2).
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The Fundação de Amparo a Pesquisa do Estado de São Paulo (FAPESP), Brazil provided partial financial support under Award 03/083917. We thank Verônica Barros and Adriana Barros whose assistance made this study possible.
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References |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionAcknowledgementsReferences |
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Armitage P (1971) Statistical Methods in Medical Research, 3rd edn. A Halsted Press Book, John Wiley and Sons, New York.
Bagger YZ, Tanko LB, Alexandersen P, Hansen HB, Mollgaard A, Ravn P, Qvist P, Kanis JA and Christiansen C (2004) Two to three years of hormone replacement treatment in healthy women have long-term preventive effects on bone mass and osteoporotic fractures: the PERF study. Bone 34,728–735.[Medline]
Bahamondes L, Perrotti M, Castro S, Faúndes D, Petta C and Bedone A (1999) Forearm bone density in users of Depo-Provera as a contraceptive method. Fertil Steril 71,849–852.[CrossRef][Web of Science][Medline]
Bahamondes L, Trevisan M, Andrade L, Marchi NM, Castro S, Diaz J and Faúndes A (2000) The effect upon the human vaginal histology of the long-term use of the injectable contraceptive Depo-Provera. Contraception 62,23–27.[CrossRef][Web of Science][Medline]
Bahamondes L, Hidalgo M, Petta CA, Diaz J, Espejo-Arce X and Monteiro-Dantas C (2003) Enlarged ovarian follicles in users of a levonorgestrel-releasing intrauterine system and contraceptive implant. J Reprod Med 48,637–640.[Web of Science][Medline]
Bahamondes L, Monteiro-Dantas C, Espejo-Arce X, dos Santos Fernandes AM, Lui-Filho JF, Perrotti M and Petta CA. A prospective study of the forearm bone density of users of etonorgeotrel- and levonorgeotrel-releasing contraceptive implants. Hum Reprod. Advance Access published October 10, 2005, 10.1093/humrep/dei358.
Barbosa I, Olsson SE, Odlind V, Goncalves T and Coutinho E (1995) Ovarian function after seven years’ use of a levonorgestrel IUD. Adv Contracept 11,85–95.[CrossRef][Web of Science][Medline]
Chetkowski R, Meldrum D, Steingold K, Randle D, Lu JK, Eggena P, Hershman JM, Alkjaersig NK, Fletcher AP and Judd HL (1986) Biologic effects of transdermal estradiol. N Engl J Med 314,1615–1620.[Abstract]
Cromer BA, Blair JM, Mahan JD, Zibners L and Naumovski Z (1996) A prospective comparison of bone density in adolescent girls receiving depot medroxyprogesterone acetate (Depo Provera), levonorgestrel (Norplant), or oral contraceptives. J Pediatrics 129,671–676.[CrossRef][Web of Science][Medline]
Cundy T, Evans MC, Roberts H, Wattie D, Ames R and Reid IR (1991) Bone density in women receiving depot medroxyprogesterone acetate for contraception. BMJ 303,13–16.
Cundy T, Cornish J, Evans M, Roberts H, Elder H and Reid I (1998) Spinal bone density in women using depot medroxyprogesterone contraception. Obstet Gynecol 92,569–573.[CrossRef][Web of Science][Medline]
Diaz S, Pavez M, Miranda P, Robertson DN, Sivin I and Croxatto HB (1982) A five-year clinical trial of levonorgestrel Silastic implants (Norplant). Contraception 25,447–456.[CrossRef][Web of Science][Medline]
Diaz S, Pavez M, Miranda P, Johansson EDB and Croxatto HB (1987) Long-term follow-up of women treated with Norplant implants. Contraception 35,551–567.[CrossRef][Web of Science][Medline]
Diaz S, Reyes MV, Zepeda A, Gonzalez GB, Lopez JM, Campino C and Croxatto HB (1999) Norplant implants and progesterone vaginal rings do not affect maternal bone turnover and density during lactation and after weaning. Hum Reprod 4,2499–2505.
Diaz J, Bahamondes L, Monteiro I, Petta C, Hildalgo MM and Arce XE (2000) Acceptability and performance of the levonorgestrel-releasing intrauterine system (Mirena) in Campinas, Brazil. Contraception 62,59–61.[CrossRef][Web of Science][Medline]
Gbolade B, Ellis S, Murby B, Randall S and Kirkman R (1998) Bone density in long-term users of depot medroxyprogesterone acetate. BJOG 105,790–794.
Hampton NRE, Rees MCP, Lowe DG, Rauramo I, Barlow D and Guillebaud J (2005) Levonorgestrel intrauterine system (LNG-IUS) with conjugated oral equine estrogen: a successful regimen for HRT in perimenopausal women. Hum Reprod 20,2653–2660.
Hidalgo M, Bahamondes L, Perrotti M, Diaz J, Dantas-Monteiro C and Petta C (2002) Bleeding patterns and clinical performance of the levonorgestrel-releasing intrauterine system (Mirena) up to two years. Contraception 65,129–132.[CrossRef][Web of Science][Medline]
Hurskainen R, Teperi J, Rissanen P, Aalto AM, Grenman S, Kivela A, Kujansuu E, Vuorma S, Yliskoski M and Paavonen J (2004) Clinical outcomes and costs with the levonorgestrel-releasing intrauterine system or hysterectomy for treatment of menorrhagia: randomized trial 5-year follow-up. JAMA 291,1456–1463.
Jia MC, Zhou LY, Dong L and Xiao B (1992) Serum SHBG levels during normal menstrual cycle and after insertion of levonorgestrel-releasing IUD. Adv Contracept 8,33–40.[CrossRef][Medline]
Kaunitz AM (2005) Depo-Provera’s black box: time to reconsider? Contraception 72,165–167.[CrossRef][Web of Science][Medline]
Lockhat FB, Emembolu JO and Konje JC (2005) The efficacy, side-effects and continuation rates in women with symptomatic endometriosis undergoing treatment with an intra-uterine administered progestogen (Levonorgestrel): a 3 year follow-up. Hum Reprod 20,789–793.
Luukkainen T, Lähteenmäki P and Toivonen J (1990) Levonorgestrel-releasing intrauterine device. Ann Med 22,85–90.[Web of Science][Medline]
Marshall D, Johnell O and Wedel H (1996) Meta-analysis of how well measures of bone mineral density predict occurrence of osteoporotic fractures. BMJ 312,1254–1259.
Monteiro I, Bahamondes L, Diaz J, Perrotti M and Petta C (2002) Therapeutic use of levonorgestrel-releasing intrauterine system in women with menorrhagia: a pilot study. Contraception 65,325–328.[CrossRef][Web of Science][Medline]
Naessen T, Olsson SE and Gudmundson J (1995) Differential effects on bone density of progestogen-only methods for contraception in premenopausal women. Contraception 52,35–39.[CrossRef][Web of Science][Medline]
Nilsson G, Haukkamaa M, Vierola H and Luukkainen T (1982) Tissue concentrations of levonorgestrel in women using a levonorgestrel-releasing IUD. Clin Endocrinol (Oxf) 17,529–536.[Medline]
Nilsson CG, Lahteenmaki PL and Luukkainen T (1984) Ovarian function in amenorrheic and menstruating users of a levonorgestrel-releasing intrauterine device. Fertil Steril 41,52–55.[Web of Science][Medline]
Perrotti M, Bahamondes L, Petta C and Castro S (2001) Forearm bone density in long-term users of oral combined contraceptives and depot medroxyprogesterone acetate. Fertil Steril 76,469–473.[CrossRef][Web of Science][Medline]
Petitti DB, Piaggio G, Metha S, Cravioto MC and Meirik O (2000) Steroid hormone contraception and bone mineral density: a cross-sectional study in an international population. Obstet Gynecol 95,736–744.[CrossRef][Web of Science][Medline]
Petta CA, Ferriani RA, Abrao MS, Hassan D, Rosa E, Silva JC, Podgaec S and Bahamondes L (2005) Randomized clinical trial of a levonorgestrel-releasing intrauterine system and a depot GnRH analogue for the treatment of chronic pelvic pain in women with endometriosis. Hum Reprod 20,1993–1998.
Raudaskoski TH, Lahti EI, Kauppila AJ, Apaja-Sarkkinen MA and Laatikainen TJ (1995) Transdermal estrogen with a levonorgestrel-releasing intrauterine device for climacteric complaints: Clinical and endometrial responses. Am J Obstet Gynecol 172,114–119.[CrossRef][Web of Science][Medline]
Raudaskoski T, Tapanainen J, Tomas E, Luotola H, Pekonen F, Ronni-Sivula H, Timonen H, Riphagen F and Laatikainen T (2002) Intrauterine 10 µg and 20 µg levonorgestrel systems in postmenopausal women receiving oral oestrogen replacement therapy: clinical, endometrial and metabolic response. BJOG 109,136–144.[Web of Science][Medline]
Robertson DN, Sivin I, Nash HA, Braun J and Dinh J (1983) Release rates of levonorgestrel from Silastic capsules, homogeneous rods and covered rods in humans. Contraception 27,483–495.[CrossRef][Web of Science][Medline]
Ronnerdag M and Odlind V (1999) Health effects of long-term use of the intrauterine levonorgestrel-releasing system. A follow-up study over 12 years of continuous use. Acta Obstet Gynecol Scand 78,716–721.[CrossRef][Web of Science][Medline]
United States Food and Drug Administration. Talk Paper Black Box Warning Added Concerning Long-Term Use of Depo-Provera Contraceptive Injection, November 17, 2004.
Volpe A, Amram A, Cagnacci A and Battaglia C (1997) Biochemical aspects of hormonal contraceptive: effects on bone metabolism. Eur J Contracept Reprod Health Care 2,123–126.[Medline]
World Health Organization. WHO Statement on Hormonal Contraception and Bone Health, July, 2005.
World Health Organization (1994) Assessment of Fracture Risk and its Application to Screening for Post-Menopausal Osteoporosis. Report of a WHO Study Group. WHO, Geneva (WHO technical report Series 843).
World Health Organization (2004) Medical Eligibility Criteria for Contraceptive Use, 3rd edn. WHO, Geneva.
Submitted on September 28, 2005; resubmitted on November 8, 2005; accepted on November 15, 2005.
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