An IUD is a small device that is inserted into the uterus to prevent pregnancy. IUDs include a hormone-releasing version, which can prevent pregnancy for 5 years, and a copper version, which is effective for 10 years. The hormonal IUD releases a small amount of the hormone progestin into the uterus, while the copper IUD releases a small amount of copper. The devices cost a few hundred dollars each, not including doctors' charges for inserting them. If a woman decides she wants to become pregnant, the device can be removed. Both types of IUD are thought to prevent pregnancy mainly by preventing fertilization of the egg by the sperm.
A number of studies have shown that today’s IUDs are safe and effective in preventing pregnancy. However, some health care providers have been cautious about recommending IUDs because an older, unsafe version of a specific IUD, the Dalkon Shield, caused serious infections and even deaths in the 1970s.
To gather more evidence on how well IUDs work, researchers supported by the Population Dynamics Branch reviewed private health insurance claims to study 90,489 women, age 15 to 44, who had an IUD inserted between 2002 and 2009.
They found that less than 1% of all women developed serious complications from the devices, regardless of their age. Between 2% and 6% of women reported pain during menstruation or absence of periods while using an IUD. Both symptoms were more common among teens than among older women (PMID: 23635730).