Typical-use failure rates in contraception
Typical-use failure rate is the real-world rate of pregnancy over a year, and the implant (a small rod under the skin) has the lowest of the methods compared.
Remember
Typical-use failure is lowest for user-independent methods (ones with nothing to remember once fitted), and the implant, at less than 0.05% a year, is the lowest of those compared. For someone who forgets regular medication, choose a user-independent method.
Every contraceptive method (anything that lowers the chance of pregnancy compared with using no method) has two failure rates. Perfect use is the rate when the method is used exactly as instructed. Typical use is the rate seen in real life, including missed pills, late injections and condoms that slip.
User-dependent methods (those that require regular action, for example every day or every time) lose a lot of effectiveness in everyday use. User-independent ones lose very little, because once an implant is in place there is nothing to remember.
The etonogestrel implant is a small rod, about the size of a matchstick, fitted under the skin of the upper arm. The hormone it releases, etonogestrel, is a progestogen, meaning a hormone similar to progesterone. The implant is a form of LARC (long-acting reversible contraception): once fitted it works for months or years, and it can be stopped whenever the user chooses.
Its typical-use failure rate is less than 0.05% a year, the lowest among the methods compared here. The copper intrauterine device (the copper coil) is also user-independent, but its rate is about 0.8% a year. The depot injection (a long-acting injection), which needs a repeat injection every 12 to 13 weeks, is about 6% a year. Pills, the patch and the vaginal ring (which needs timely removal and replacement) are about 9% a year, and male condoms are about 18% a year.
The exam trap is comparing methods by perfect-use figures, where pills look almost as good as the implant. A method that relies less on the user remembering has a smaller gap between perfect and typical use.
Key facts
- Typical use
- the failure rate seen in real life, including missed pills, late injections and condom slippage.
- Implant
- less than 0.05% a year, the lowest typical-use failure rate of the methods compared here.
- Copper coil
- about 0.8% a year in typical use, low but still higher than the implant's.
- Depot injection
- late or missed repeat injections (one is needed every 12 to 13 weeks) give a typical-use failure rate of about 6% a year.
- Pills, patch and vaginal ring
- about 9% a year in typical use.
- Male condom
- about 18% a year in typical use.
- Against no method
- every method lowers the chance of pregnancy, so a group using nothing has the most pregnancies.
Exam traps
- A pill that is more than 99% effective with perfect use can still have a typical-use failure rate of about 9% a year, because missed pills raise it.
- A copper coil is user-independent and has a low typical-use failure rate of about 0.8% a year, but that is still higher than the implant's figure of less than 0.05% a year.
- A depot injection avoids daily dosing, but late or missed repeat injections give a typical-use failure rate of about 6% a year, well above the implant's.
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