Intrauterine devices (IUDs)

Plastic and copper intrauterine device (IUD).

IUDs, once known as ‘coils’ or ‘loops’, are a widely used form of birth control which became prominent in the 20th century. These small devices fit into the uterus and provide long-term contraception. An IUD is fitted by a trained practitioner and can stay in place for a number of years. They remain popular, especially in China, although there are questions about their long-term safety.

In 1909, German doctor Richard Richter first described an IUD. It was a ring made of silkworm gut inserted into the uterus. Ernst Gräfenberg developed a flexible ring of silk suture 20 years later, which he later modified by wrapping around silver wire. The ‘Gräfenberg ring’ became the first IUD to be used in numbers, but it was associated with high infection rates. Like all IUDs it acted as a foreign object, which promoted an inflammatory response from the uterus. This creates a hostile environment for sperm which are then neutralised.

New IUDs made from plastic or metal came onto the market during the 1960s and became very popular. Copper was particularly effective. Copper-based IUDs and inert plastic IUDs are still used. A third type of hormone-releasing IUDs has been developed in recent years. They are usually referred to separately as intrauterine systems (IUSs).

Poor monitoring of new devices in the 1960s and 1970s caused health fears. An American product called the Dalkon Shield was associated with a number of deaths. The product was removed and product testing greatly improved. However, popular doubts about the safety of IUDs persist.