birth-control, condomsVarious forms of birth control are labeled as XX% effective. What does this mean? If a condom is, say, 99% effective, and my wife and I have sex 100 times, can I assume the condom will fail 1 of those times?
Birth control effectiveness metrics are a measurement of the percentage of couples who become pregnant using a given birth control method as measured over a specified period of time. The CDC uses perfect use over a one-year period of time, and while other studies may be different or study different use cases, most of them use that same baseline.
However, the length of time is less important when you’re comparing birth control methods. As long as you’re comparing statistics from the same source using the same length of study time, the comparative information is going to be roughly the same as if you picked a longer or shorter time.
It’s worth noting that there are some statistics out in the wild about typical use failure rates. Typical use refers to what people tend to actually do out in the wild, whereas perfect use refers to fully-aware proper use. As an example, since many men don’t know how to use condoms properly, the typical use failure rate for condoms is 15%, while the perfect use rate is 2%.
Overall, the World Health Organization says condoms have a 2% failure rate when used perfectly and consistently. But the typical failure rate is much higher, at 15%, with the typical use of condoms. (source)
The short answer is, it’s the percentage of couples who did not become pregnant while relying on the tested birth control method. If you find a failure rate online, chances are good that they’re talking about the perfect use failure rate over one year of use.
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