Birth Control Efficacy Rates

A large systemic review of FABMs was published in 2018.
Full paper – Effectiveness of Fertility Awareness–Based Methods for Pregnancy Prevention
There is also a neat associated interactive infographic.
This link will open a 2-page PDF table comparing hormonal and non-hormonal forms of birth control. The Symptothermal method of FAM is one of the most effective for trying to avoid pregnancy, with a 0.4% unintended pregnancy rate in a year. The medical journal source is included in the PDF.
This link will take you to the highest quality scientific study carried out to date on a symptothermal FAM method (Sensiplan). It gives an efficacy rate of 99.6% (when abstinence is used in the fertile window).
BUDDY SYSTEM – This link will open an article outlining the mathematical effectiveness of using two birth control methods together (such as condoms + withdrawal @ 99.92% effectiveness). Some ladies practicing FAM will use two birth control methods together in their fertile window to be extra conservative. (Note – this article may be slightly outdated because the efficacy of some methods has changed in the latest surveys.)