Contraceptive prevalence in the United States is typically calculated according to the most effective method of contraception reported. This could theoretically underestimate the number of women using fertility-awareness based methods (FABMs), including those who use other methods (e.g., condoms) during the fertile window, but the extent of any such underestimation has not been assessed.

We used data from the 2013–2015 National Survey of Family Growth to examine the extent to which women report use of an FABM alone or with other methods. We investigated FABM use patterns and compared demographic profiles of FABM users versus other contraceptive users. We considered how to most appropriately define FABM prevalence.

One in six (16.5%) female contraceptors 15–44 reported use of multiple contraceptive methods in their month of interview. Among women reporting current FABM use, 67% used it alone or with withdrawal, 24% also used condoms or emergency contraception, and 9% also used hormonal contraception or sterilization. An FABM was the most effective method reported for 2.2% of current contraceptive users; while 3.2% of contraceptors reported any current FABM use. We posit an FABM prevalence of 3% (1,113,000 users) among US female contraceptors (2013–2015). FABM users had similar sociodemographic characteristics as other method users, but were more likely married.

Currently, consideration of multiple method use has modest implications for estimation of FABM prevalence among contraceptors (i.e., an increase from 2.2% to 3%). However, multiple method use patterns with FABMs may merit special consideration if FABM use continues to increase.

Researchers and providers need to be familiar with the unique patterns of use among FABM users in order to more effectively measure and counsel about these methods.