Contraceptive Failure Rates: New Estimates and Advances in Measurement

Kathryn Kost, Guttmacher Institute

Access to contraception empowers individuals with resources to exercise autonomy over whether or when to become pregnant. But contraceptive use does not guarantee pregnancy cannot occur; methods are imperfect, and many individuals can and will experience contraceptive failure Method effectiveness is one of many factors affecting method choice, though millions of sexually active people consider how methods are ranked in effectiveness in their decisions to use one method over another. With this in mind, we broke with a longstanding approach used in prior studies and produce new “typical-person” contraceptive failure rates, to represent the expected risk of a contraceptive failure that an average person – rather than an average user of a particular method – might face with use of a specific method. Based on nationally representative population data, these estimates account for observed variation in reported sexual activity among US users of different methods, in use of multiple methods and in demographic characteristics of those using different methods (age, parity, union status, and education). These new estimates improve our understanding of the relative effectiveness of contraceptive methods and are better suited than typical-use estimates for that purpose. Further, they may be more appropriate than prior estimates for non-US populations.

Keywords: Family Planning and Contraception, Sexual and Reproductive Health and Rights, Bayesian methods

See extended abstract.