The intrauterine device (IUD), also known as an intrauterine contraceptive device (IUCD or ICD), is a small, T-shaped birth control device that is inserted into the uterus to prevent pregnancy. IUDs are a form of long-acting reversible contraception (LARC). IUDs are a safe and effective birth control method that can be divided into two major categories based on the mechanism the device uses to prevent pregnancy: hormonal (levonorgestrel) IUDs and copper IUDs. Both types of IUDs can be used in most women, including adolescents, those who have never been pregnant, and those who have previously had children. They do not affect breastfeeding and can be inserted immediately after delivery. They may also be used immediately after an abortion. Globally, 19.4% of women of reproductive age use intrauterine contraception according to 2019 data. The IUD has a more invasive insertion procedure than other birth control methods. However, among birth control methods, IUDs, along with other contraceptive implants, result in the greatest satisfaction among users. Both hormonal and copper IUDs have failure rates of <1%, meaning less than 1 in 100 individuals with an IUD have an unintended pregnancy. In comparison, combined hormonal contraception methods (oral pill, vaginal ring, transdermal patch, etc.) have a failure rate of about 2% with perfect use and 4-7% with typical use. Barrier methods, such as the male condom, have a failure rate of approximately 13% and fertility awareness methods (often referred to as natural family planning or the rhythm method), have a failure rate of 22%. Once an IUD is removed, even after long-term use, fertility returns to normal rapidly. Hormonal IUDs often reduce menstrual bleeding by up to 90% or stop menstruation altogether. Users may experience daily spotting following insertion, and it can take up to six months to see a decrease in bleeding. Copper IUDs are preferred by some as a non-hormonal birth control option, but they can increase the amount and duration of menstrual bleeding by approximately 50% and lead to worsening of menstrual cramps. More serious potential complications of both types of IUD include expulsion (3–5%) and perforation of the uterus (one in 1,000). IUDs can also be used as emergency contraception for the prevention of pregnancy immediately following unprotected sex. Copper IUDs are considered the most effective form of emergency contraception, with only 0.1% of those with a copper IUD placed within 5 days of unprotected sex becoming pregnant. Hormonal IUDs are also an acceptable method for emergency contraception; however, there is less data regarding effectiveness. Though concern exists among some whether an IUD is only a contraceptive, studies indicate that users discharged roughly the same number of decaying fertilized embryos (4.5%) as did non-users.
History The first IUD was developed in 1909 by the German physician Richard Richter of Waldenburg. Unlike modern intrauterine devices, early interuterine (from Latin inter-, meaning "between", as opposed to intra-) devices crossed both the vagina and the uterus, causing a high rate of pelvic inflammatory disease. 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. In 1935, Gräfenberg, who was Jewish, was in jail in Berlin and Margaret Sanger paid a ransom to have him released. He moved to the United States and opened a private practice in New York, New York. His colleagues H. Hall and M. Stone took up his work after his death and created the stainless steel Hall-Stone 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 nylon string to facilitate IUD removal. Lippes and his friend Paul Bronnenkant, a plastics developer, crafted the first Lippes Loop in Bronnenkant's kitchen, heating and molding the plastic on cookie sheets in the oven. His trapezoid-shaped 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. One of these first-generation IUDs was the Dalkon Shield, whose poor design caused bacterial infection and led to thousands of lawsuits. Although it was removed from the market, the Dalkon Shield had a lasting, negative impact on IUD use and reputation in the United States. The invention of the copper IUD in the 1960s introduced the capital T-shaped design used by most modern IUDs. U.S. physician Howard Tatum determined this shape would work better with the space of the uterine cavity. He predicted this would reduce rates of IUD expulsion. Further, Tatum and Chilean physician Jaime Zipper discovered that copper could be an effective spermicide and developed the first copper IUD. Improvements by Tatum led to the creation of the TCu380A (ParaGard), which is the preferred copper IUD since 1997. The hormonal IUD was also invented in the 1960s and 1970s with the goal of mitigating the increased menstrual bleeding associated with copper and inert IUDs. The first model, Progestasert, lasted for one year of use and was quickly discontinued. The Mirena hormonal IUD was released in 1976.
China In China, the use of IUDs by state health services was part of the government's efforts to limit birth rates. From 1980 to 2014, 324 million women were inserted with IUDs, in addition to the 107 million who had tubal ligation. Until the mid-1990s, the state-preferred IUD was a stainless steel ring, which had a higher rate of complications compared to other types of IUD. It gave rise to the idiom shànghuán (上环), meaning "insert a loop". Since then, IUDs include T and V shapes, the former being the most common and easiest to remove.
Mechanism
The main mechanisms of action of IUDs occur before fertilization, by preventing sperm from ever reaching the egg. The specific mechanism for preventing sperm from reaching the egg differs by type of IUD.
Hormonal
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