Many of us have no idea how effective (or ineffective as the case may be), different birth control methods actually are. Doctors will tell you the effectiveness rates of some birth control options based on their “Perfect Use” efficacy rates and for others, you will hear their “Typical Use” efficacy rates. Perfect Use efficacy rates, also known as "Correct Use", reflect what happens when a contraceptive method is used perfectly all of the time. Typical Use efficacy rates, also known as "Actual Use", reflect what happens in the real world when we factor in human error. The chart below shows the difference in Typical Use efficacy vs. Perfect Use efficacy rates in some of the most commonly used user-controlled family planning methods:
Note that "user-controlled" methods have a somewhat greater difference between Typical Use and Perfect Use efficacy than "doctor-controlled" methods such as IUD's and hormonal implants.
So after reading the above you may be asking,
“If the pill is 99.9% effective as claimed, how come 9% of women in a given year using the pill will get pregnant? “
“Why are condoms described as 98% effective, yet 18 out of 100 women using them exclusively will get pregnant in a given year?”
There are many reasons someone might use a particular method incorrectly. A user might forget to take her pill, put the condom on incorrectly, or decide to engage in risky behavior on what she knows are potentially fertile days.
It is interesting to note that CycleBeads is the most effective of fertility awareness-based methods in terms of Typical Use. Also, in looking at the efficacy studies where this Typical Use efficacy rate for CycleBeads was determined, almost all users who became pregnant unintentionally during the efficacy trials, did so during the first three months of use. In order to understand the effectiveness in the real world, users were only asked to self-determine if their cycles were in the 26-32 day range (instead of going through a stringent screening process), and it is likely that users did not have cycles in the appropriate range from the beginning.
That’s why important to understand the difference between Perfect Use and Typical Use. You might think your birth control method is 99.9% effective, but in actuality, mistakes happen. It’s far more important that people pick birth control options that they can use consistently and correctly than that they pick the one that is most effective in theory.