INTRODUCTION —
The intrauterine device (IUD) is the most used method of long-acting reversible contraception because of its high efficacy and safety, ease of use, and cost effectiveness. It provides a nonsurgical option for pregnancy prevention that is as effective as surgical sterilization. The most frequently used IUDs have a plastic frame and release either copper or a progestin to enhance the contraceptive action of the device.
Several terms are used to describe IUDs, including IUD and intrauterine contraception; the hormonal IUD or progestin-containing device is also referred to as an intrauterine system. In this topic, we use the term IUD for all types of IUDs.
This topic will discuss types of IUDs and their mechanism of action. Issues related to IUD selection, use in specific populations, removal, side effects, and complications are discussed separately:
●(See "Intrauterine contraception: Candidates and device selection".)
●(See "Intrauterine contraception: Insertion and removal".)
●(See "Intrauterine contraception: Management of side effects and complications".)
In this topic, when discussing study results, we will use the terms "woman/en" or "patient(s)" as they are used in the studies presented. We encourage the reader to consider the specific counseling and treatment needs of transgender and gender-expansive individuals.
COUNSELING POINTS (ALL IUD TYPES)
Prevalence of use — IUDs are the most commonly used method of reversible contraception globally, with use rates ranging from <1 to >30 percent depending on the country [1,2]. Use of IUDs has increased in the United States: Between 2002 and 2016, IUD use rose from 2 to 14 percent among United States women using contraception [3-8]. Actively informing patients about benefits, risks, and common side effects of IUDs appears to improve consideration and acceptance of the method [9].
Mechanism of action — IUDs primarily prevent conception by inhibiting fertilization, although there are multiple mechanisms (table 1). IUDs are not abortifacients [10-15] as they do not interrupt established pregnancies.
●Mechanisms – Pregnancy appears to be prevented by a foreign body effect induced by the IUD frame and by local changes caused by the released medication.
•Foreign body effect – When the uterus is exposed to a foreign body, a sterile inflammatory reaction occurs, which is toxic to sperm and ova and impairs fertilization [12,14,16-18]. The production of cytotoxic peptides and activation of enzymes lead to inhibition of sperm motility, reduced sperm capacitation and survival, and sperm phagocytosis which also inhibit fertilization [19,20]. These cytotoxic effects are supported by studies in which fallopian tubes of IUD users were flushed but no sperm or fertilized ova were found [12,14].
•Copper – The addition of copper enhances the cytotoxic inflammatory response within the endometrium and prevents fertilization by impacting sperm migration, viability, and acrosomal reaction [11,17,18,21,22].
•Levonorgestrel (LNG) – The addition of LNG thickens cervical mucus, which acts as a barrier to the upper genital tract (ie, reduces sperm access to the upper tract and thereby prevents fertilization), causes endometrial decidualization and glandular atrophy, and may inhibit the binding of the sperm and egg by increasing glycodelin A production, which further impairs fertilization [23-25].
●Minimal impact on ovulation – Copper IUDs do not impact ovulation. For LNG IUD users, most cycles are ovulatory. With initial insertion, ovulation rates may decrease (ie, ovulation is suppressed) and then return to normal as the LNG level drops over time. During the first year of IUD use, LNG 52 mg IUD users ovulated in 45 percent of cycles while users of lower-dose IUDs ovulated in 88 to 97 percent of cycles [26-29].
●Not an abortifacient – There is no evidence that IUDs disrupt an implanted pregnancy [30]. Studies of IUD users were unable to find embryos or detect human chorionic gonadotropin, indicating that transient, or chemical, pregnancies were not occurring [17,31,32]. Despite the evidence that IUDs do not interrupt pregnancy (ie, are not an abortifacient), a 2019 survey of 893 US physicians reported that 17 percent believed that IUDs caused abortion [33].
Benefits, risks, and patient satisfaction
●Benefits – There are multiple benefits of IUD use, including:
•Highly effective pregnancy prevention (>99 percent) (figure 1).
•Does not require regular adherence from user to maintain high effectiveness.
•Long acting.
•Rapidly reversible. Resumption of fertility after discontinuation is rapid and similar for IUDs [26-29,34], progestin-releasing implants [35,36], and contraceptive pills, rings, and patches [37,38].
•Few medical contraindications for most women. (See "Intrauterine contraception: Candidates and device selection", section on 'Contraindications'.)
•Suitable for teens and nulliparous women.
•Few side effects.
•Private and does not interfere with the spontaneity of sex.
•Avoidance of exogenous estrogen (both IUD types) and hormones (copper IUD only).
•Highly cost-effective with long-term use.
•Reduced risk of cervical, endometrial, and ovarian cancers [39]. Data specific to the LNG IUDs are available below. (See 'Risk of cancer' below.)
-Cervical cancer – A meta-analysis of 16 studies assessing the incidence of cervical cancer in IUD users reported that women with any history of IUD use were approximately 30 percent less likely to develop cervical cancer (summary odds ratio [OR] 0.64, 95% CI 0.53-0.77) [40]. The proposed mechanism is an altered cellular immune response resulting from device insertion and presence [41,42]. These studies primarily collected data about nonhormonal IUD use.
-Endometrial cancer – Both copper and LNG IUDs reduce the risk of endometrial cancer; the LNG IUD suppresses the endometrial growth and the copper IUD creates a local inflammatory response [39].
-Ovarian cancer – Results on the effect of IUDs on ovarian cancer risk are conflicting, although most studies show a reduced risk [39]. A meta-analysis of 11 studies (9 case control, 2 cohort) reported a reduced rate of ovarian cancer with ever-use of an IUD (summary OR 0.68, 95% CI 0.62-0.75) [43]. The mechanisms by which an IUD might reduce cancer risk and the impact of device type on cancer risk are not known.
•Noncontraceptive benefits. (See 'Noncontraceptive benefits' below.)
●Risks – The risk of either complication or pregnancy with IUD use is low overall. Most of the risks associated with IUD use occur at the time of placement and include difficult insertion, bleeding, infection, and perforation of the uterus. Insertion is often associated with cramping and/or pain, which typically resolves quickly. Detailed discussions of complications are presented in related content. (See "Intrauterine contraception: Management of side effects and complications".)
●Patient satisfaction and method continuation – The above factors contribute to high patient satisfaction and method continuation rates [44-46]. A 2015 United States study of over 5300 women ages 14 to 45 years using either the LNG or copper 380 mm2 IUDs reported one-, two-, three-, four-, and five-year continuation rates of 88, 79, 70, 62 and 52 percent for the LNG IUD and 85, 77, 70, 64, and 56 percent for the copper IUD [46-48]. A Finnish study including almost 18,000 women using an LNG IUD reported continuation rates at one, two, three, four, and five years of 93, 87, 81, 75, and 65 percent, respectively [44]. For comparison, United States women using short-acting methods (ie, depot medroxyprogesterone acetate or hormonal contraceptive pills, patch, or ring) reported a 30 percent three-year contraceptive continuation rate in one study.
Cost effectiveness — All IUDs are highly cost-effective; although the initial cost of the device and insertion can be high, the overall cost decreases with each year of use because no additional expenditure is required. At five years of use, the IUD is one of the most cost-effective methods of reversible contraception available [49]. A 2015 United States cost analysis study that compared the cost of long-acting and short-acting reversible contraceptives calculated that long-acting reversible contraception (including the copper and LNG 52 mg IUD) began saving money after 2.1 years of use when compared with short-acting reversible contraception that included pills, patch, ring, or injection [50].
Risk of sexually transmitted infections and pelvic inflammatory disease — While IUDs do not protect against sexually transmitted infections (STIs), presence of an IUD is not associated with an increased risk of pelvic inflammatory disease (PID) should an STI be acquired [51-53]. Data conflict as to whether or not the risk of STI or PID is greater for users of copper or levonorgestrel IUDs [54,55]. Patients at risk for STI are advised to use condoms (internal or external) to reduce STI risk.
•(See "External (formerly male) condoms".)
•(See "Internal (formerly female) condoms".)
COPPER IUDS
Device types and characteristics — There are two commonly available copper IUDs, each named for the amount of copper in the device.
●Copper dose and device size – Copper-containing IUDs contain either 380 mm2 or 175 mm2 of copper.
•Copper 380 mm2 – The copper 380 mm2 IUD (commercial name ParaGard) is approved for up to 10 years of use [56,57] This device has a T-shaped polyethylene frame with 380 mm2 of exposed surface consisting of fine copper wire wound around a vertical stem and copper collars on each of the horizontal arms [57]. The device size measures 32 mm horizontally and 36 mm vertically; the placement applicator has a 4.4 mm diameter [58]. A 3 mm ball at the base of the stem decreases the risk of cervical perforation (picture 1) [59]. A white or clear polyethylene monofilament string is knotted through this ball. The frame contains barium sulfate to make it radiopaque. The device is latex free.
The copper 380 mm2 IUD can be inserted for emergency contraception for at least five days (120 hours) from unprotected intercourse and has the lowest pregnancy rate (<0.1 percent) [60,61]. The device can then be left in place to provide ongoing contraception [62]. (See "Emergency contraception", section on 'What are the emergency contraception methods?'.)
•Copper 175 mm2 – The copper 175 mm2 device (commercial name Miudella) is approved for three years of use [63]. It has a flexible nitinol (nickel-titanium alloy) frame with 175 mm of exposed copper. The copper sleeves are located on the distal arms and the base. The device measures 32 mm horizontally and 30 mm vertically; the placement applicator has a 3.7 mm diameter [63]. The device comes preloaded in an applicator with a rounded tip and a polypropylene monofilament retrieval thread pre-cut to a length of 7.8 cm. The device does not contain barium sulfate or latex. The devices compatibility with magnetic resonance imaging (MRI) is listed as conditional. The copper 175 mm2 IUD is not to be used for emergency contraception.
●Use for emergency contraception – The copper 380 mm2 is an established method of emergency contraception. The 175 mm2 device is contraindicated for use as emergency contraception. A complete discussion of emergency contraception is available separately. (See "Emergency contraception".)
●Copper serum levels – Serum copper levels are approximately 216 mcg/dL for the 380 mm2 and 63.5 ng/mL for the 175 mm2 device [57,63]. While serum copper levels are higher in copper 380 mm2 users compared with nonusers and above the normal blood copper level range; however, this increase in circulating copper does not have a negative clinical impact unless the patient has a contraindication to copper (eg, Wilson disease) or allergy [64].
●Copper allergy – Clinically relevant allergy to copper is extremely rare [65]. (See "Intrauterine contraception: Candidates and device selection", section on 'Contraindications'.)
Efficacy
●Comparison of copper IUDs
•380 mm2 IUD – With perfect use of the copper 380 mm2 IUD, the probability of pregnancy in the first year is 0.6 percent; with typical use, the first-year pregnancy rate is 0.5 to 0.8 percent (table 2) [16,66-68].
•175 mm2 IUD – In the initial trials, Pear Indices for years 1, 2, and 3 were 0.94, 1.60, and 0.60 percent, respectively [63]. The cumulative three-year Pearl Index was 1.05 percent (95% CI 0.66-1.60). Available data are from two initial trials that included 1601 healthy women aged 17 to 74 years [58,69].
●Comparison of copper and levonorgestrel IUDs – While failure rates for both IUDs are low overall (figure 1), the rates of failure with the copper IUD are slightly higher than with progestin-releasing IUDs, although conflicting data exist [67]. In one study of over 61,000 women, the copper IUD first-year failure rate was 0.52 versus 0.06 pregnancies per 100 woman-years for the LNG 52 mg IUD [67]. This is similar to the one-year pregnancy rate of 0.7 reported in the copper IUD package insert [70]. In addition, the ectopic pregnancy rate was higher for copper IUDs than the LNG 52 mg IUD (0.08 versus 0.02 ectopic pregnancies per 100 woman-years). While the proportion of ectopic pregnancies was higher for women with LNG IUDs compared with copper IUDs (27 versus 15 percent), the overall incidence rate of ectopic pregnancy was higher for copper IUD users because of the somewhat higher overall failure rate. Of note, the copper IUD study group contained more than 30 types of copper IUDs, which may have impacted the results. As an example, IUDs with less than 380 mm2 of copper and inert IUDs are less effective than those containing ≥380 mm2 of copper [71,72].
●Comparison of copper IUDs and tubal ligation – In a study comparing interval laparoscopic tubal ligation with either copper 380 mm2 or levonorgestrel IUDs (all types), unintended pregnancy rates were similar between tubal ligation and the copper 380 mm2 IUD (adjusted incident rate ratio [aIRR] 0.92, 95% CI 0.82-1.05) but lower with the levonorgestrel IUDs (aIRR 0.72, 95% CI 0.64-0.82). Postpartum tubal ligation was not included in this retrospective cohort study of Medicaid insurance claim data from California.
Additional discussion of permanent contraception is available separately. (See "Overview of female permanent contraception".)
●Impact of younger patient age – Women under age 25 experience a slightly higher failure rate, most likely because they are more fertile than older women. These failure rates are comparable to surgical sterilization [73,74]. (See "Female interval permanent contraception: Procedures".)
Routine and extended duration of use
●Routine use – The copper 380 mm2 IUD is approved for 10 years of use; the copper 175 mm2 IUD is approved for three years of use [57,63].
●Extended use of the 380 mm2 IUD – In appropriately counseled patients, who are typically older and have lower fertility, the copper 380 mm2 IUD can be used for more than 10 years before removal and/or replacement. Extended use of the 175 mm2 IUD is not advised as data are not available.
•Supporting data – Several studies support extended use of the copper 380 mm2 beyond 10 years [75-77]. In two studies of 314 women who used the copper 380 mm2 for an additional two years (10 to 12 years from insertion), no pregnancies were reported [75,76]. Additionally, no pregnancies were reported in the subgroup of eight women who used the device for up to 16 years [76].
•Potential benefits – We counsel patients about the advantages of extended use of the copper 380 mm2 (cost savings, prolongation of contraception, and avoidance of an additional intrauterine procedure). However, for patients with strong preferences for replacement at 10 years, we follow the package insert recommendation to remove or replace the copper 380 mm2 at 10 years.
•Impact of patient age and counseling – In addition to patient preference, extended use depends on patient age at insertion because age impacts fertility.
-<25 years – For patients younger than 25 years at the time of copper 380 mm2 IUD placement, we recommend replacing the IUD after 10 years of use because younger women are more fertile.
-25 to 34 years – For patients age 25 to 34 years at the time of copper 380 mm2 IUD placement, the IUD may be left in place for up to 12 years [75,76].
-≥35 years – For patients age 35 years or older at the time of copper 380 mm2 IUD placement, we recommend leaving the IUD in place until menopause if the patient is happy with the method and still requires contraception [78].
Noncontraceptive benefits — Noncontraceptive benefits of the copper IUD include continued menstrual cyclicity (both devices) and reduced risk of endometrial and cervical cancers (data from studies of the copper 380 mm2 IUD) [39,40,79-82].
Avoid radiofrequency treatment — Patients with copper IUDs are advised to avoid medical treatments and/or equipment that use high levels of radiofrequency energy, such as diathermy [57,63]. There is concern that the copper components could become hot and cause injury. LNG IUDs do not contain metal and thus are not contraindicated.
LEVONORGESTREL IUDS
Devices and characteristics — The levonorgestrel (LNG)-releasing IUDs are available in three different formulations in the United States:
●LNG dose, device size, and duration of use – The LNG IUDs are T-shaped devices that release LNG in four different doses [26-29].
•LNG 52 mg IUDs – This IUD has an initial LNG release rate of approximately 20 mcg/day, which declines to an average release of 10 mcg/day at five years [29]. These devices are approved by the US Food and Drug Administration (FDA) for eight years (abbreviated LNG 52 mg, commercial names Mirena and Liletta) [26,29,83-85].
•LNG 19.5 mg IUD – The initial LNG release rate is 17.5 mcg/day, which declines to 7.4 mcg/day at five years and is FDA approved for five years of use (abbreviated LNG 19.5, commercial name Kyleena) [27].
•LNG 13.5 mg IUD – The initial LNG release rate is approximately 14 mcg/day, which declines to 5 mcg/day at three years and is FDA approved for three years of use (abbreviated LNG 13.5, commercial name Skyla) [28].
●Frame and inserter characteristics
•LNG 52 mg devices – Both 52 mg IUDs consist of a T-shaped polyethylene frame measuring 32 by 32 mm, with a collar containing 52 mg of LNG dispersed in polydimethylsiloxane attached to a vertical stem [26,29]. A string is attached to the distal end of the stem. The insertion tube diameter for the 52 mg LNG IUDs ranges from 4.4 to 4.8 mm. Both devices contain barium in the frame to make them detectable by radiograph.
•LNG 19.5 and 13.5 mg devices – The LNG 19.5 and the LNG 13.5 also use the T-shaped design. In contrast with the LNG 52 mg IUDs, the LNG 19.5 mg and LNG 13.5 mg devices have a smaller frame (28 by 30 mm versus 32 by 32 mm) and are smaller in diameter (3.8 mm inserter versus 4.4 mm) [26-29]. The smaller diameter may allow easier insertion for patients with very small uterine cavities or cervical stenosis, but there are no comparative trials. The LNG 19.5 and LNG 13.5 contain a silver ring at the top of the stem to distinguish them on ultrasound and barium in the frame to make them detectable by radiograph [27,28].
●LNG serum and tissue concentrations – The progestin effect of hormone-releasing IUDs is primarily at the level of the endometrium [86]. As an example, the endometrial concentration of LNG is 1000 times higher with the LNG-releasing IUDs compared with the LNG subdermal implant [87]. However, the high endometrial concentration from the IUDs does not result in a high plasma concentration; the absolute plasma LNG levels are much lower. For the 13.5 mg, 19.5 mg, and 52 mg LNG IUDs, the plasma LNG concentration is highest seven days postinsertion with levels between 100 and 250 pg/mL. There is a gradual decline over time with wide individual variation [26-29,88-90]. This level is half that seen with progestin implants (350 pg/mL) and much less than that associated with progestin-only pills (1500 to 2000 pg/mL) [91,92] but high enough to cause systemic side effects in some users. Serum estradiol levels are not affected [89].
●Use for emergency contraception – The LNG 52 mg IUDs can be used for emergency contraception; the LNG 13.5 and 19.5 mg devices should not be used for emergency contraception. (See "Emergency contraception", section on 'What are the emergency contraception methods?'.)
Efficacy — All levonorgestrel IUDs have low (1 percent or less) rates of unintended pregnancy (ie, failure).
●Comparison of levonorgestrel IUDs – With perfect use of the LNG 52 mg, the probability of pregnancy in the first year is 0.1 percent; with typical use, the first-year pregnancy rate is 0.1 to 0.2 percent (table 2) [67,93,94]. With five years of continuous LNG 52 mg use, the cumulative pregnancy rate is 0.7 percent [26,95,96]. The clinical trial for the LNG 52 mg reported cumulative pregnancy rates of 0.14 percent at one year and 0.87 percent at four years [97]. In a phase three trial of the LNG 19.5 and LNG 13.5 devices, the cumulative pregnancy rates were 0.2 and 0.4 percent at one year and 0.9 and 1.0 percent at three years, respectively [98]. These rates are comparable to those of sterilization procedures (figure 1) [73]. (See "Overview of female permanent contraception", section on 'Counseling and informed consent'.)
●Comparison of copper and levonorgestrel IUDs – While failure rates for copper and levonorgestrel IUDs are low overall (figure 1), the rates of failure with the copper IUD are slightly higher than with progestin-releasing IUDs, as discussed in detail above. (See 'Efficacy' above.)
●Comparison with permanent contraception – In a study comparing interval laparoscopic tubal ligation with either copper 380 mm2 or levonorgestrel IUDs (all types), unintended pregnancy rates were lower with the levonorgestrel IUDs (adjusted incident rate ratio [aIRR] 0.72, 95% CI 0.64-0.82) but similar between tubal ligation and the copper 380 mm2 IUD (aIRR 0.92, 95% CI 0.82-1.05) [74].
•(See 'Efficacy' above.)
•(See "Overview of female permanent contraception", section on 'Counseling and informed consent'.)
●Risk of ectopic pregnancy – While the overall risk of pregnancy is low with LNG IUDs, if a pregnancy is conceived, ectopic pregnancy is more common in patients using LNG IUDs compared with copper IUDs. Thus, individuals who conceive while using any IUD should be evaluated for ectopic pregnancy. (See 'Efficacy' above.)
In a study of over 61,000 European women with a newly inserted IUD, the proportion of ectopic pregnancies was higher in LNG users compared with copper IUD users (27 versus 15 percent) [67]. However, as discussed above, the overall incidence risk of ectopic pregnancy was lower with LNG IUDs because of the lower absolute risk of pregnancy. A smaller cohort study reported similar low rates of ectopic pregnancy between LNG and copper IUD users (both 0.5 per 1000 woman-years) [99]. A retrospective cohort study of over 2000 Swedish women diagnosed with an ectopic pregnancy found the overall risk of an ectopic pregnancy was low among LNG IUD users. However, the risk was higher among users of the 13.5 mg (Pearl Index [PI] 0.136, 95% CI 0.106-0.176) and 19.5 mg (PI 0.037, 95% CI 0.021-0.067) LNG IUD compared with the 52 mg LNG IUD (PI 0.009, 95% CI 0.006-0.014) [100].
Extended use of LNG 52 mg IUDs — Both LNG 52 mg IUDs are approved for up to eight years but studies support extended use may be reasonable [26,29,77,84,85,101-103]. The LNG 19.5 and 13.5 have a lower LNG dose, and there is no evidence supporting extended use of these IUDs past the approved duration [78].
In an extension of a trial that initially enrolled participants up to eight years of LNG 52 mg IUD use, no pregnancies were reported by the participants who continued the IUD for 9 (n = 83) or 10 years (n = 77) of total use [104]. In both groups, the majority of patients were younger than 40 years at study completion (64 patients at 9 years [77 percent] and 44 patients at 10 years [57 percent]).
Noncontraceptive benefits — Noncontraceptive benefits of 52 mg LNG IUDs include reduction in heavy menstrual bleeding, anemia, dysmenorrhea, endometriosis-related pain, and endometrial hyperplasia [39,40,105-113]. The use of the LNG 52 mg IUD for treatment of heavy menstrual bleeding is FDA approved [26,29]. LNG use of 52 mg LNG IUDs for these other noncontraceptive indications is off-label but a common practice that is supported by strong medical evidence. For obese individuals with complex atypical hyperplasia, several observational studies have reported improved resolution with LNG IUD treatment compared with systemic progestin therapy [114,115]. There is also a reduction in the risk of endometrial cancer and ovarian cancer with LNG IUDs.
The use of the IUD or surgical procedures to treat heavy menstrual bleeding is reviewed in detail elsewhere.
There is minimal information on the noncontraceptive benefits of the LNG 19.5 and 13.5 IUDs, although it is probable that they also reduce heavy menstrual bleeding, anemia, and dysmenorrhea.
Risk of cancer — LNG IUD use is likely associated with a small increased risk of breast cancer but reduced risk of endometrial and ovarian cancers. Limitations of the available studies include observational data, choice of comparator group (eg, users of other hormonal contraceptives or users of nonhormonal contraceptive methods), duration of study follow-up, prior pregnancy and timing, and baseline cancer risk of study participants, among other variables. The small increased risk of breast cancer is balanced against the larger reductions in endometrial and ovarian cancers on an individual patient basis.
●Breast cancer – The body of evidence suggests a small increased absolute risk of breast cancer with LNG IUD use [116-122], although not all studies agree [123]. In an administrative database study that matched first-time LNG IUD users (any dose) with nonusers of hormonal contraception, there were fewer total cases of breast cancer among LNG IUD users (0.92 versus 1.14 percent), but use was associated with a small increase in overall risk of breast cancer (hazard ratio 1.4, 95% CI 1.2-1.5) [119]. This is similar to the risk reported in an earlier publication by the same research group (RR 1.2, 95% CI 1.1 to 1.33) and in other observational studies with LNG IUD use [116-118,120-122]. For comparison, the increased risk of breast cancer conferred by LNG IUD use appears to be similar to the risk conferred by obesity, alcohol use, or estrogen-progestin contraceptive pills, if the range of published increased risk is considered. We find these comparisons useful in counseling patients and helping each patient understand their individual risk.
•(See "Overview of the risks and benefits of alcohol consumption", section on 'Breast cancer'.)
LNG IUD use is not advised for patients with active breast cancer. (See "Intrauterine contraception: Candidates and device selection", section on 'Contraindications'.)
●Other gynecologic cancers – LNG IUD use has been associated with lower risk of endometrial and ovarian cancer (20 to 30 percent risk reduction for endometrial cancer and 13 to 30 percent risk reduction for ovarian cancer) [39,120,122,124,125]. In a study of Swedish register data comparing over 500,000 LNG users with over 1.5 million nonusers, LNG users had reduced risks of endometrial (adjusted hazard ratio [aHR] 0.67, 95% CI 0.56-0.80) and ovarian cancer (aHR 0.86, 95% CI 0.75-0.99). The risk of cervical cancer also appears to be lower, but with a more modest reduction (aHR 0.91, 95% CI 0.84-0.99) [120]. However, one study reported an increase in cervical intraepithelial neoplasia in LNG IUD users compared with copper IUD users; comparison with the general population was unknown [81,83].
•(See "Endometrial carcinoma: Epidemiology, risk factors, and prevention".)
•(See "Epithelial carcinoma of the ovary, fallopian tube, and peritoneum: Incidence and risk factors".)
•(See "Invasive cervical cancer: Epidemiology, risk factors, clinical manifestations, and diagnosis".)
IMPACT OF IUDS ON BLEEDING PATTERN —
In general, copper IUDs are associated with heavier menstrual bleeding while levonorgestrel (LNG) IUDs can cause lighter bleeding, amenorrhea, or minimal change, depending on the LNG dose.
Copper IUDs — Individuals considering the copper IUDs are counseled that menses may be heavier, longer, or more painful, particularly in the first several cycles after insertion [57,63]. The initial increases in bleeding and pain generally resolve by six months of use [126]. The amount of baseline menstrual bleeding the patient has prior to copper IUD insertion does not appear to impact the 12-month device continuation rate. Patients with baseline heavy menstrual bleeding are not more likely than those without to remove the device [127]. Nonsteroidal anti-inflammatory drugs (NSAIDs) may decrease heavy menstrual bleeding in copper IUD users, although studies are limited [128].
●Bleeding volume – While the average monthly menstrual blood loss may increase by up to 55 percent throughout the duration of copper IUD use, it rarely leads to anemia. A systematic review reported the hemoglobin concentration decreased by 0.36 to 0.94 g/dL over 12 months in copper 380 mm2 IUD users who were not anemic at baseline [129]. We discuss with patients that typical menstrual blood loss per cycle is 5 to 80 mL based on clinical data, and may increase with copper IUD use [130,131]. Discussions of menstrual volume are available in other content. (See "Abnormal uterine bleeding in nonpregnant reproductive-age patients: Terminology, evaluation, and approach to diagnosis".)
●Discontinuation rates for bleeding and/or pain – The initial trial data suggest that the lower dose of the copper 175 mm2 IUD results in less bleeding and cramping, as reflected by the discontinuation rates, compared with the copper 380 mm2 IUD. At 1, 2, and 3 years of use, the discontinuation rates for 175 mm2 users were 8.5, 5.1, and 3.2 percent, respectively, while discontinuation rates for copper 380 mm2 users were 11.9, 9.8, and 7.0 percent, respectively [57,63].
●Comparison of copper 380 mm2 and LNG IUDs – In a study of over 3800 women using either the copper 380 mm2 or the LNG 52 mg, at three months the copper IUD users reported more cramping (63 versus 32 percent), increased bleeding volume (71 versus 12 percent), and increased bleeding frequency (41 versus 33 percent) compared with LNG 52 mg users [126]. Importantly, these symptoms improved rapidly, and at six months the copper IUD users reported symptom reduction to levels similar to the LNG 52 mg users (cramping 14 versus 12 percent, increased bleeding volume 19 versus 8 percent, increased bleeding frequency 13 versus 11 percent). (See "Intrauterine contraception: Management of side effects and complications", section on 'Post-insertion bleeding' and "Intrauterine contraception: Management of side effects and complications", section on 'Irregular bleeding and/or cramping'.)
Levonorgestrel-releasing IUDs — For the LNG-releasing IUDs, the most common changes in bleeding patterns include prolonged bleeding (59 percent), unscheduled bleeding (up to 52 percent), amenorrhea (6 to 20 percent), and spotting (23 to 31 percent) at the end of one year of use [26-28,97,132]. Women should be reassured that the changes in bleeding patterns are a side effect of the hormone on the uterine lining and are not dangerous. All women should be counseled that intermenstrual bleeding is common, especially with the onset of use, and improves by six months of use [26,28,97,126]. A study including 3001 LNG 52 mg users who were surveyed at three and six months of IUD use reported that, by six months, 62 percent of reported lighter bleeding and 55 percent reported decreased frequency of bleeding [126]. The management of these and other hormonal side effects, such as breast tenderness, mood changes, and acne, is discussed in detail separately. (See "Intrauterine contraception: Management of side effects and complications".)
While changes in bleeding patterns are common with the 52 mg, 19.5 mg, and 13.5 mg LNG IUDs, the amenorrhea rate differs substantially among the devices. After one year of use, amenorrhea is reported by approximately 20 percent of LNG 52 mg IUD users, 12 percent of LNG 19.5 mg users, and 6 percent of LNG 13.5 mg users [26-28,97,132,133]. At the end of three years of use, 30 to 50 percent of LNG 52 mg IUD users reported amenorrhea compared with 20 and 12 percent of women using the LNG 19.5 mg and LNG 13.5 mg, respectively [26-28,97]. Therefore, women who prefer to avoid menstrual bleeding may benefit from a 52 mg device, and those who prefer the reassurance of monthly menstruation may benefit from the 19.5 mg or 13.5 mg devices. Both groups must be counseled that the desired menstrual change may not occur; some women with the 52 mg devices will continue to have monthly periods, and some with the lower dose devices will become amenorrheic.
Bleeding-related discontinuation rates — With supportive counseling, most patients are able to tolerate the changes in bleeding patterns, and discontinuation rates are low overall for all devices. In a study of over 3800 women using either the copper 380 mm2 or the LNG 52 mg, the overall satisfaction rate for both the copper IUD and the LNG IUD was greater than 90 percent at six months of use [126]. Only 7 percent of LNG IUD users and 8 percent of copper IUD users discontinued by six months [134]. In the six-year LNG 52 mg clinical trial, 2.3 percent of women discontinued the device early because of bleeding complaints compared with a 12 percent overall early discontinuation rate [97]. Similarly, in the three-year LNG 13.5 clinical trial, the early discontinuation rates were 4.6 percent for bleeding complaints and 18 percent overall [28]. For comparison, other reasons for discontinuation of the LNG 13.5 IUD included device expulsion (3.2 percent), acne/seborrhea (2.9 percent), abdominal pain (2.5 percent), dysmenorrhea/uterine spasms (2.0 percent), and pelvic pain (1.8 percent). (See "Intrauterine contraception: Management of side effects and complications", section on 'Irregular bleeding and/or cramping' and "Intrauterine contraception: Management of side effects and complications", section on 'Continued bleeding and cramping'.)
RISK OF EXPULSION —
The incidence of expulsion is 3 to 10 percent for the copper IUDs and 3 to 6 percent for the levonorgestrel IUD in the first year of use [16,57,63,66,75,135,136]. The symptoms and risk factors of expulsion are discussed separately.
●(See "Intrauterine contraception: Management of side effects and complications", section on 'Expulsion'.)
●(See "Contraception: Postabortion", section on 'Intrauterine device'.)
●(See "Contraception: Postpartum counseling and methods", section on 'Expulsion'.)
OTHER IUD TYPES —
Multiple other IUD types and shapes have been used globally (picture 2).
Inert IUDs — Unmedicated IUDs are approved for use outside the United States and are popular because they can remain in place for 20 years or more. The devices are composed of inert materials such as plastic or stainless steel. Flexible stainless steel rings visible on radiographs, but with no string, were widely used in China [137]. The pregnancy rates for the Lippes Loop vary by device size and range from 1 to 4.8 per 100 women-years [138,139]. The higher failure rate of the stainless steel ring compared with copper T IUDs (10.6 versus 1.7 percent) led the Chinese State Family Planning Commission to stop production of the ring in 1993 and to encourage the use of copper or levonorgestrel (LNG)-releasing IUDs instead [16,137,140].
As medicated IUDs are more effective, we recommend replacing inert IUDs with LNG-releasing or copper IUDs, especially for women below age 40, as they have higher fertility rates. We also inform women ages 40 and older that LNG and copper IUDs are more effective than inert IUDs but do not encourage switching if the patient is happy with her device.
Frameless IUDs — Frameless IUDs, which are available outside of the United States, contain either copper or LNG that has been attached to a nonresorbable filament. The GyneFix 330 is made up of copper cylinders threaded onto a polypropylene suture instead of the plastic frame common to other IUDs [141,142]. The FibroPlant is a frameless LNG-releasing IUD consisting of a nonresorbable thread attached to a fibrous delivery system that releases 14 or 20 mcg of LNG per day [143]. These devices are anchored to the endometrium using an insertion technique that requires additional training as the technique is different from the other types of IUDs. The intrauterine ball SCu300A is comprised of copper beads strung on a memory alloy wire that curls into a ball shape on insertion into the uterus [144].
Advantages of these systems include small size, high efficacy, and high tolerability. They may be as effective as conventional IUDs and more adaptable to variations in the shape of the uterine cavity [145,146]. However, the risk of expulsion may vary depending on the IUD shape [147].
SOCIETY GUIDELINE LINKS —
Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Contraception".)
INFORMATION FOR PATIENTS —
UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topics (see "Patient education: Intrauterine devices (IUDs) (The Basics)" and "Patient education: Long-acting methods of birth control (The Basics)" and "Patient education: IUD placement (The Basics)" and "Patient education: IUD removal (The Basics)")
●Beyond the Basics topic (see "Patient education: Long-acting methods of birth control (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Device types and prevalence of use – The two common categories of IUDs are copper-containing and levonorgestrel-releasing (LNG) devices. Globally, an average of 23 percent of contraceptive users report having an IUD, which makes these devices the most used reversible contraceptive worldwide. Both the copper and LNG-releasing devices are available in multiple formulations. (See 'Counseling points (all IUD types)' above.)
●Mechanism of action – Multiple mechanisms appear to contribute to the contraceptive action of IUDs (table 1). The primary mechanism is prevention of fertilization due to by a foreign body effect induced by the IUD frame and by local changes caused by the released medication. LNG IUDs also cause thickening of cervical mucus. (See 'Mechanism of action' above.)
●Benefits of use – There are multiple benefits to IUD use, including high effectiveness and little maintenance for the user (figure 1), which result in high user satisfaction rates. The IUD is also cost-effective when used over multiple years. (See 'Benefits, risks, and patient satisfaction' above and 'Cost effectiveness' above.)
●Copper IUDs – The copper 380 mm2 has a T-shaped polyethylene frame with 380 mm2 of exposed surface consisting of fine copper wire wound around a vertical stem and copper collars on each of the horizontal arms; a 3 mm ball at the base of the stem decreases the risk of cervical perforation (picture 1). The copper 380 mm2 can also be used for emergency contraception and left in place for continued contraception. In 2025, the copper 175 mm2 device (commercial name Miudella) is approved for three years of use. The device is anticipated to be available at the end of 2025. (See 'Copper IUDs' above.)
•Efficacy – With perfect use, the probability of pregnancy in the first year is 0.7 percent; with typical use, the first year pregnancy rate is 0.5 to 0.8 percent (table 2). While failure rates for both copper and LNG-releasing IUDs are low overall, the rates of failure with the copper IUD are somewhat higher than with progestin-releasing IUDs. (See 'Efficacy' above.)
•Duration of use – The copper 380 mm2 is approved by the US Food and Drug Administration (FDA) to remain in place for 10 years. However, this may vary elsewhere since the use of the copper 380 mm2 beyond 10 years is supported by several studies. (See 'Routine and extended duration of use' above.)
•Impact on menses – Women considering the copper IUD are counseled that menses may be heavier, longer, or more painful, particularly in the first several cycles after insertion. These changes in menstrual symptoms often improve over time and generally do not cause women to remove the IUD. (See 'Copper IUDs' above.)
●Levonorgestrel IUDs – There are four types of LNG-releasing IUDs available in the United States, with progestin-release rates ranging from 14 to 20 mcg/day (picture 3). The progestin effect of hormone-releasing IUDs is primarily at the level of the endometrium. (See 'Devices and characteristics' above.)
•Efficacy – With perfect use of the LNG 52 mg IUDs, the probability of pregnancy in the first year is 0.1 percent; with typical use, the first-year pregnancy rate is 0.1 to 0.2 percent (table 2). (See 'Efficacy' above.)
-Duration of use – The duration of use varies with the type of LNG IUD. The LNG 52 mg devices are approved for up to eight years of use by the FDA (commercial names Mirena and Liletta). The LNG 19.5 mg and 13.5 mg have lower LNG doses and are approved for five and three years respectively. There is no evidence supporting extended use of the LNG 19.5 mg and 13.5 mg IUDs. (See 'Extended use of LNG 52 mg IUDs' above.)
•Impact on menses and related benefits – Noncontraceptive benefits of 52 mg LNG IUDs include reduction in heavy menstrual bleeding, anemia, dysmenorrhea, endometriosis-related pain, and endometrial hyperplasia. (See 'Noncontraceptive benefits' above.)
●Other IUD types – Multiple types of IUDs are available globally. Popular devices include inert and frameless IUDs (available outside the United States).
•Inert or unmedicated IUD – Inert, or unmedicated, IUDs are popular because they can remain in place for 20 years or more. The devices are composed of inert materials such as plastic or stainless steel. (See 'Inert IUDs' above.)
•Frameless IUD – Frameless IUDs, which are available outside of the United States, contain either copper or LNG that has been attached to a nonresorbable filament. Advantages of these systems include small size, high efficacy, and high tolerability. They may be as effective as conventional IUDs and more adaptable to variations in the shape of the uterine cavity. (See 'Frameless IUDs' above.)
ACKNOWLEDGMENTS —
The UpToDate editorial staff acknowledges Gillian Dean, MD, MPH, and Alisa Goldberg, MD, MPH, who contributed to an earlier version of this topic review.