Effectiveness of a salivary progesterone-based fertility awareness contraceptive method

We aimed to assess the 6-month effectiveness of a salivary progesterone fertility awareness-based (FAB) method at preventing pregnancy, used with condoms when desired.

From May 2022 to April 2023, we performed a six-month prospective, observational study on sexually active, menstruating women in Germany desiring FAB methods for contraception. Study participants tracked their menstrual cycle by providing daily samples of saliva to a device which measures salivary progesterone levels and uses an algorithm to estimate the fertile window. The accompanying app informed users when the fertile window was beginning and reminded users to abstain or use a barrier method during that time. We identified pregnancy via user reports of positive pregnancy tests or clinical diagnosis. We used Kaplan-Meier life tables to estimate six-month typical-use effectiveness.

Three hundred participants contributed 6 months of data for a total of 1492 valid cycles, equivalent to 115 person-years. Mean user age was 30.5 ± 5.2 years. We estimated six-month typical-use effectiveness of 96% (95% confidence interval [CI]: 93, 98) of the salivary progesterone FAB method (with barrier as back-up). No adverse events occurred. The majority of participants rated the usability of the device (74%) and strips (57%) as good or very good.

Our data suggest that salivary progesterone tracking method has an effectiveness consistent with other similar FAB methods and is easy to use.

These findings support salivary progesterone tracking as an effective digital contraceptive, expanding options for patients prioritizing non-hormonal, user-controlled methods.