The modern intrauterine device (IUD) is a form of birth control in which a small 'T'-shaped device, containing either copper or progesterone, is inserted into the uterus. IUDs are a form of long-acting reversible contraception, which is the most effective type of reversible birth control. As of 2002, IUDs were the most widely used form of reversible contraception, with nearly 160 million users worldwide.
The types of intrauterine devices available and the names they go by differ by location.
In the United States, there are two types available:
In the United Kingdom, there are over 10 different types of copper IUDs available. In the UK, the term IUD refers only to these copper devices. Hormonal intrauterine contraception is considered to be a different type of birth control and is labeled with the term intrauterine system (IUS).
Copper IUDs primarily work by disrupting sperm mobility and damaging sperm so that they are prevented from joining with an egg. Copper acts as a spermicide within the uterus, increasing levels of copper ions, prostaglandins, and white blood cells within the uterine and tubal fluids. The increased copper ions in the cervical mucus inhibit the sperm's motility and viability, preventing sperm from traveling through the cervical mucus or destroying it as it passes through. Copper IUDs have a first year failure rate ranging from 0.1 to 2.2%.
Most non-hormonal IUDs have a plastic T-shaped frame that is wound around with pure electrolytic copper wire and/or has copper collars (sleeves). The arms of the frame hold the IUD in place near the top of the uterus. The Paragard TCu 380a measures 32 mm (1.26") horizontally (top of the T), and 36 mm (1.42") vertically (leg of the T).
Copper IUDs containing noble metals are becoming increasingly popular because they are more resistant to corrosion. In the "Gold T IUD", which is made in Spain and Malaysia, there is a gold core, which further prevents the copper from fragmenting or corroding. GoldringMedusa is a differently-shaped German version of the Gold T .Another form of AuCu IUD is called Goldlily which is made by the Hungarian company, Radelkis. Goldlily consists of a layer of copper wires wrapped around an original layer of gold wires, and it provides electrochemical protection in addition to ionic protection..
Silver IUDs also exist. Radelkis also makes Silverlily, which is similar to Goldlily, and GoldringMedusa is available in an AgCu version as well. Nova-T 380 contains a strengthening silver core, but does not incorporate silver ions themselves to provide electrochemical protection.
 Other shapes of IUD include the so-called U-shaped IUDs, such as the Load and Multiload, and the frameless IUD that holds several hollow cylindrical minuscule copper beads. It is held in place by a suture (knot) to the fundus of the uterus. It is mainly available in China, Europe, and Germany, although some clinics in Canada can provide it.
Advantages of the copper IUD include its ability to provide emergency contraception up to five days after unprotected sex. It is the most effective form of emergency contraception available. It contains no hormones, so it can be used while breastfeeding, and fertility returns quickly after removal. Copper IUDs are also available in a wider range of sizes and shapes than hormonal IUDs. Disadvantages include the possibility of heavier menstrual periods and more painful cramps.
In addition to copper, noble metal and progestogen IUDs, patients in China can get copper IUDs with indomethacin. This non-hormonal compound reduces the severity of menstrual bleeding, and these coils are popular.
The hormonal I.U.D. (brand name Mirena) does not increase bleeding as copper-containing IUDs do. Rather, they reduce menstrual bleeding or prevent menstruation altogether, and can be used as a treatment for menorrhagia (heavy periods).
Use of Mirena results in much lower systemic progestogen levels than other very-low-dose progestogen-only hormonal contraceptives.
As of 2007, the LNG-20 IUS – marketed as Mirena by Bayer – is the only IntraUterine System available. First introduced in 1990, it releases levonorgestrel (a progestin) and may be used for five years per its label but 7 years per researchers/clinicians (?who). With use of Mirena, the hormones are localized to the uterine area unlike oral contraceptives and other systemic contraception (e.g. depot medroxyprogesterone, etonogestrel implant).
IUDs work by preventing fertilization rather than via preventing implantation. Some within the antiabortion movement have claimed that IUDs are an abortifacient in an effort to decrease their use as a contraceptive, this position however is not supported by the evidence.
The history of IUDs dates back to the interuterine devices of the early 1900s. Unlike IUDs, interuterine devices crossed both the vagina and the uterus, causing a high incidence of pelvic inflammatory disease in a time period when gonorrhea was endemic. The first IUD was developed by the German physician, Dr. Richter of Waldenburg. His device was made of silkworm gut and was not widely used.
Dr. Ernst Gräfenberg, another German physician after whom the G-spot is named, created the first Ring IUD, Gräfenberg's ring, made of silver filaments. His work was suppressed during the Nazi regime, when contraception was considered a threat to Aryan women. He moved to the United States, where his colleagues Dr. H. Hall and Dr. M. Stone took up his work after his death and created the stainless steel Hall-Stone Ring. A Japanese doctor named Tenrei Ota also developed a silver or gold IUD called the Precea or Pressure Ring.
Dr. Jack Lippes helped begin the increase of IUD use in the United States in the late 1950s. In this time, thermoplastics, which can bend for insertion and retain their original shape, became the material used for first-generation IUDs. Lippes also devised the addition of the monofilament nylon string, which facilitates IUD removal. His trapezoid shape Lippes Loop IUD became one of the most popular first generation IUDs. In the following years, many different shaped plastic IUDs were invented and marketed. These included the infamous Dalkon Shield, whose poor design caused bacterial infection and led to thousands of lawsuits. Although the Dalkon shield was removed from the market, it had a lasting, negative impact on IUD use in the United States.
The invention of the copper IUD in the 1960s brought with it the capital 'T' shaped design used by most modern IUDs. US physician, Dr. Howard Tatum determined that the 'T' shape would work better with the shape of the uterus, which forms a 'T' when contracted. He predicted this would reduce rates of IUD expulsion. Together, Tatum and Chilean physician Jaime Zipper discovered that copper could be an effective spermicide and developed the first copper IUD, TCu200. Improvements by Dr. Tatum led to the creation of the TCu380A (ParaGard), which is the current gold standard for copper IUDs.
The hormonal IUD was also invented in the 1960s and 1970s. The first model, Progestasert, was conceived of by Dr. Antonio Scommengna and created by Dr. Tapani J.V. Luukkainen, but the device only lasted for one year of use. Progestasert was manufactured until 2001. The only commercial hormonal IUD still currently available, Mirena, was also developed by Dr. Luukkainen and released in 1976.
A lower-dose T-shaped IntraUterine System named Femilis is being developed by Contrel, a Belgian company. Contrel also manufactures the FibroPlant-LNG, a frameless IUS. FibroPlant is anchored to the fundus of the uterus as the GyneFix IUD is. Although a number of trials have shown positive results, FibroPlant is not yet commercially available.
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