Typically used for long-term contraception, the intrauterine device (IUD) is also an effective emergency contraceptive if implanted after unprotected sex. Two IUDs, which are T-shaped pieces of plastic, are available in the United States. One IUD releases copper, and the other releases the hormone levonorgestrel(Drug information on levonorgestrel). The IUD containing copper is the model that has been studied for use as emergency contraception.
In a systematic review of 42 studies that involved the effectiveness of 8 different types of IUDs for emergency contraception, researchers in China identified 7034 women who had an IUD inserted after unprotected sex.1 The review covered the period from 1979 to 2011.
Of these 7034 IUD insertions, 10 (0.14%) pregnancies were recorded. In the studies reviewed, IUD insertion occurred from 2 days to more than 10 days after unprotected sex. However, when used for emergency contraception, insertion of IUDs within 5 days after unprotected sex probably offers the best protections against pregnancy.
IUDs are 99.9% effective as emergency contraception. Morning after pills are estimated to be 97% to 98% effective, but failure rates and adverse effects increase with repeated use. In addition, some research has shown that the morning after pills do not work as well in overweight and obese women. Compared with normal-weight women (BMI < 25), risk of pregnancy was 1.5 times greater in overweight women (BMI 25 – 30) and more than 3 times greater in obese women (BMI >= 30).2 Either form of emergency contraception is considered effective, however.
Despite its effectiveness and long-lasting contraceptive benefits, recommendation of the copper IUD for emergency contraception is rare and most women are unaware that it is an option for emergency contraception.3 Although same-day insertion of a copper IUD might disrupt clinic flow and cause scheduling challenges, health care providers should adopt a patient-centered approach and inform patients that insertion of a copper IUD is a highly effective option for emergency contraception.4 In addition, cost is a potential barrier to women choosing an IUD over a morning after pill for emergency contraception.5
- IUDs containing copper are 99.9% effective when used as emergency contraception.
- Insertion of an IUD within 5 days of intercourse probably provides the best protection against an unwanted pregnancy, but more research is needed to determine how delay between unprotected sex and insertion impacts the effectiveness of the device.
- Most patients are not aware of the benefits of copper IUDs. Obstetricians and gynecologists should better inform patients about all options for emergency and long-term contraception.