Pregnancy among women who have IUDs is very rare. According to the American Congress of Obstetricians and Gynecologists (ACOG), IUDs are one of the most effective forms of birth control, with a failure rate of less than 1 percent during the first year of typical use.

How do you know if your IUD has failed?

You can take an OTC test on the first day of your missed period. If your IUD has caused your periods to be irregular — or to stop completely — you should wait to one to two weeks after you suspect your IUD failed to take an OTC test. These tests are almost 99 percent accurate .

What could cause an IUD to fail?

An IUD can fail if it is not placed correctly by the healthcare provider, or if it's expelled from the uterus (1).