Intrauterine device

Based on Wikipedia: Intrauterine device

In 1930s Germany, a Jewish physician named Ernst Gräfenberg was developing something the Nazi regime considered an existential threat to the Aryan race: birth control. His invention—a small ring made of silver filaments designed to sit inside a woman's uterus—was suppressed, and Gräfenberg eventually fled to the United States. But the device he created would go on to become one of the most effective and widely used forms of contraception in human history. Today, we call it the intrauterine device, or IUD.

The story of the IUD is a story of brilliant innovation, catastrophic failure, political manipulation, and ultimately, vindication. It involves Nazi eugenics, thousands of lawsuits, China's one-child policy, and a small piece of copper that can prevent pregnancy more reliably than almost anything else medicine has to offer.

What an IUD Actually Is

Picture a small object, about the size of a quarter, shaped like the letter T. This device gets placed inside the uterus—the muscular organ where a fetus would develop during pregnancy—and once there, it prevents pregnancy with remarkable effectiveness.

There are two main types, and they work in completely different ways.

The first type releases hormones. Specifically, it slowly releases a synthetic version of progesterone called levonorgestrel. This hormone thickens the mucus at the entrance to the uterus, creating a barrier that sperm simply cannot penetrate. Imagine trying to swim through honey instead of water. The sperm never reach the egg, and pregnancy never occurs. As a side effect, these hormonal IUDs often reduce or completely stop menstrual bleeding—a feature that many users consider a significant benefit.

The second type contains copper. No hormones, no synthetic chemicals—just copper wrapped around the plastic frame. And here's where biology gets interesting: copper ions are toxic to sperm. They damage sperm cells and destroy their ability to swim effectively. The copper also triggers a mild inflammatory response inside the uterus, and the fluid produced as part of that response contains enzymes that are lethal to sperm. It's like deploying a chemical weapon precisely targeted at reproductive cells.

Both types have failure rates below one percent. That means fewer than one in a hundred people using an IUD will experience an unintended pregnancy. Compare that to birth control pills, which fail about two percent of the time even with perfect use, or condoms, which fail about thirteen percent of the time in typical use. The rhythm method—tracking fertility cycles and avoiding sex during fertile periods—fails about twenty-two percent of the time.

The IUD is, statistically speaking, one of the most reliable ways to prevent pregnancy that humans have ever invented.

A Troubled History

The first intrauterine device appeared in 1909, created by a German physician named Richard Richter. But these early designs had a fundamental flaw: they extended from the vagina into the uterus, crossing the cervix. This created a direct pathway for bacteria to travel from the outside world into the uterine cavity, causing rampant infections called pelvic inflammatory disease.

Ernst Gräfenberg's silver ring, developed in the 1920s, was an improvement. (Gräfenberg, incidentally, is also the physician after whom the G-spot is named—he had wide-ranging interests in reproductive anatomy.) His ring sat entirely within the uterus, reducing infection risk. But his work was suppressed under Nazi rule, when contraception was viewed as a threat to the German birth rate. After he emigrated to America, colleagues continued developing his design, eventually creating the stainless steel Hall-Stone Ring.

The late 1950s brought a revolution. A physician named Jack Lippes began working with thermoplastics—materials that can be bent for insertion but spring back to their original shape once in place. He also added the nylon string that hangs through the cervix, allowing doctors to easily check the device's position and remove it when needed. His trapezoid-shaped "Lippes Loop" became one of the most popular IUDs of its era.

Then came disaster.

The Dalkon Shield, introduced in the 1970s, had a fatal design flaw. Its removal string was made of multiple filaments encased in a sheath, and bacteria could wick up between the filaments like water climbing a paper towel. The result was an epidemic of pelvic infections, some leading to sepsis, infertility, and death. Thousands of lawsuits followed. The manufacturer went bankrupt.

The Dalkon Shield was removed from the market, but its damage extended far beyond its victims. It created a lasting stigma against IUDs in the United States that persisted for decades. An entire generation of American women grew up believing IUDs were dangerous, even as the devices were safely and effectively used by hundreds of millions of women in the rest of the world.

The Modern Era

The copper IUD as we know it today emerged in the 1960s. An American physician named Howard Tatum realized that a T-shape would conform better to the triangular space inside the uterus than the loops and shields that came before. Working with Chilean physician Jaime Zipper, he discovered copper's spermicidal properties and developed the first copper IUD. Tatum's subsequent improvements led to the TCu380A—sold in the United States as ParaGard—which remains the gold standard for copper intrauterine contraception.

The hormonal IUD followed a similar path. Early versions like the Progestasert only lasted a year and were quickly abandoned. But in 1976, a device called Mirena was released, and hormonal IUDs finally became practical for long-term use. Today's hormonal IUDs can remain effective for anywhere from three to eight years, depending on the specific product.

Modern IUDs share some important characteristics. Once removed, fertility returns almost immediately—typically within days. They do not cause infertility. They do not increase infection risk. The fears that lingered after the Dalkon Shield debacle were specific to that flawed design, not to the concept of intrauterine contraception itself.

The Chinese Experience

Nowhere has the IUD played a larger role in public policy than in China. Under the government's efforts to limit population growth—including the famous one-child policy—IUDs became a tool of state control. Between 1980 and 2014, 324 million women had IUDs inserted through state health services. Another 107 million underwent tubal ligation, a permanent form of sterilization.

The practice became so common that it entered the language. The phrase "shànghuán," meaning "insert a loop," became a euphemism for receiving an IUD. Until the mid-1990s, the government-preferred device was a stainless steel ring—a design with higher complication rates than modern T-shaped IUDs. These rings also lacked removal strings, making them difficult to take out. Doctors in other countries who later encountered Chinese immigrants seeking IUD removal often had no experience with these particular devices.

This history illustrates both the power and the potential for abuse inherent in highly effective contraception. The same device that can liberate a woman from unwanted pregnancy can also be used as an instrument of coercion when placed by a government rather than chosen by an individual.

How Insertion Works

Getting an IUD placed is a medical procedure, but not a surgical one. It typically takes five to ten minutes and can be done in a regular doctor's office.

The physician first inserts a speculum—the same device used during a Pap smear—to visualize the cervix. After cleaning the cervix, the doctor uses a small instrument called a tenaculum to gently grasp and stabilize it. This step also straightens out the passage into the uterus, which naturally curves when relaxed.

Next comes the measurement. A thin probe called a uterine sound determines the depth of the uterine cavity. This measurement ensures the IUD will be placed correctly—too shallow and it might fall out, too deep and it could perforate the uterine wall.

Finally, the IUD itself is loaded into a narrow insertion tube, threaded through the cervix, and released into position. The arms of the T spring open, anchoring the device in place. The removal string hangs down through the cervix into the vagina, where it can be checked periodically and eventually used for removal.

Pain experiences vary dramatically. Some women describe the sensation as intense cramping. Others feel only a brief pinch. A small percentage report almost no discomfort at all. The American College of Obstetrics and Gynecology now recommends that all patients be offered pain control options, including anti-inflammatory medications, anxiety medication, numbing gel applied to the cervix, or numbing injections around the cervix. This last option—called a paracervical block—is highly effective but underutilized in the United States.

Removal is generally easier than insertion because nothing needs to pass through the cervix. The doctor simply grasps the strings and pulls the IUD out. The arms of the T fold down, and the device slides through the cervical opening.

Emergency Contraception

Here's something many people don't know: the copper IUD is the most effective form of emergency contraception available.

When people think of emergency contraception, they usually think of pills like Plan B. But if a copper IUD is inserted within five days of unprotected sex, the pregnancy rate is just 0.1 percent. That's roughly ten times more effective than emergency contraceptive pills.

The mechanism is straightforward. Copper's spermicidal effect works quickly, and even if fertilization has already occurred, the changes copper causes in the uterine lining can prevent implantation. Once the IUD is in place, it also provides ongoing contraception—a significant advantage over pills, which only address the immediate situation.

Hormonal IUDs can also serve as emergency contraception, though the evidence for their effectiveness in this role is less robust.

Side Effects and Complications

No medical intervention is without risks, and IUDs are no exception.

The most common complication is expulsion—the device spontaneously leaving the uterus. This happens in about three to five percent of cases. It's most likely in the first few months after insertion, and it's more common in women who have never been pregnant, whose uterine muscles may be less accommodating.

More serious but rarer is perforation—the IUD poking through the uterine wall into the abdominal cavity. This occurs in roughly one in a thousand insertions. It usually happens at the time of insertion rather than later and may require surgery to retrieve the device.

The two types of IUD have different side effect profiles beyond these shared risks.

Hormonal IUDs often cause changes in bleeding patterns. Many users experience spotting for the first few months, followed by dramatically reduced menstrual bleeding—up to ninety percent reduction, or complete cessation of periods. For some women, this is the primary reason they choose a hormonal IUD. For others, the absence of a monthly period feels unsettling, even though it's medically safe. These devices can also increase the risk of ovarian cysts, though most such cysts resolve on their own. Some users report headaches, mood changes, or depression, though studies on this association have produced mixed results.

Copper IUDs have the opposite effect on menstruation. They typically increase menstrual bleeding by about fifty percent and can worsen menstrual cramps. For women who already have heavy or painful periods, this can be a significant drawback. On the other hand, copper IUDs contain no hormones at all—for women who want to avoid synthetic hormones for any reason, this makes them the clear choice.

Who Can Use an IUD

The short answer: almost everyone with a uterus.

IUDs can be used by adolescents, by women who have never been pregnant, and by women who have had multiple children. They don't interfere with breastfeeding. They can be inserted immediately after childbirth or immediately after an abortion or miscarriage.

For years, doctors believed IUDs were inappropriate for women who hadn't yet had children, partly due to lingering fears from the Dalkon Shield era. But current medical guidelines specifically recommend IUDs for young and nulliparous women—those who have never given birth. The only additional consideration is that younger women and those who haven't been pregnant may have slightly higher expulsion rates and should be aware of this possibility.

Once an IUD is removed, fertility returns rapidly. This is true even after many years of use. The device prevents pregnancy only while it's in place; it has no lasting effect on reproductive capacity.

A Global Perspective

As of 2019, about 19.4 percent of women of reproductive age worldwide use intrauterine contraception. In some countries, particularly in Asia, rates are much higher. In others, particularly the United States, rates are lower—though American IUD use has been increasing as the stigma from the Dalkon Shield era finally fades.

The availability of specific devices varies by country. In the United Kingdom, more than ten different copper IUD models are available, and the term "IUD" refers specifically to copper devices. Hormonal intrauterine contraception is called an "intrauterine system" or IUS. In the United States, both types are generally called IUDs, with brand names like ParaGard for copper and Mirena, Liletta, Kyleena, and Skyla for hormonal versions.

Research consistently shows that among all forms of birth control, IUDs—along with contraceptive implants that go in the arm—generate the highest user satisfaction. Despite the more invasive insertion procedure compared to simply taking a pill or using a condom, people who choose IUDs overwhelmingly report being happy with their choice.

Perhaps that's because the IUD does what it promises. You get it placed once, and then you don't have to think about contraception for years. No daily pills to remember. No prescriptions to refill. No condoms to buy. Just quiet, invisible, remarkably effective protection—a small T-shaped object doing its work in silence, while you go about your life.