It turns out that there is an extremely safe and effective way to prevent pregnancy after unprotected intercourse: using an intrauterine device (IUD). According to Kelly Cleland of Princeton and her colleagues, IUDs are at least ten times more effective than hormonal emergency contraception. Unfortunately, IUDs aren’t without their drawbacks.
IUDs are small T-shaped copper devices that are inserted into the uterus. The copper is toxic to sperm. Some IUD devices also release hormones that thicken the cervical fluid so sperm cannot enter the cervix. When inserted within five days of unprotected sex, the IUD failure rate is only 0.1%.
Hormonal emergency contraceptives, known as ‘morning-after pills’ (brand names Plan B and Next Choice) should be used within three days of unprotected sex. They contain levonorgestrel, which prevents ovulation, fertilization and implantation. The failure rate of this method is between 1-3% according to Cleland, but up to 11% according to Planned Parenthood. This may be because hormonal contraception becomes less effective as body mass index increases. IUDs are not affected by body mass index.
Despite their clear superiority in effectiveness, IUDs are rarely offered to women seeking emergency contraception. There are probably two main reasons for this. One, the devices must be inserted by medical personnel. Not only is this not the case for morning-after pills, but because women can stock up on the pills ahead of time, they can avoid the need to even see a doctor postcoital. Given the political climate in the U.S. today, it may be all but impossible for a woman to find a clinic that can administer an emergency IUD within the necessary time frame.
Second, there’s the cost. A typical IUD can cost well over $500. In contrast, morning-after-pills cost as little as $10. Though to be fair, once inserted, IUDs will prevent pregnancies for up to ten years.
Image of IUD by Nevit Dilmen, 2011.