This study aims to compare the accuracy of fertile window identification with the contraceptive app Natural Cycles against the Rhythm Method and SDM.
Researchers collected menstruation dates, BBT, and LH test results anonymously from Natural Cycles app users. Researchers determined the fraction of GDs and WGDs allocated by the various algorithms over 12 cycles. For comparison of Natural Cycles and the Rhythm Method, Researchers analyzed 26,626 processes.
Natural Cycles’ algorithms allocated 59% GDs in cycle 12, while the fraction of WGDs averaged 0.08%. The Rhythm Method requires monitoring six processes, resulting in no GDs or WGDs in cycles 1–6. In cycle 7, 49% GDs and 0.26% WGDs were allocated. GDs and WGDs decreased to 43% and 0.08% in cycle 12. The probabilities of WGDs on the day before ovulation with Natural Cycles were 0.31% and 0%, and 0.80% with the Rhythm Method. The likelihood of WGDs on the day before ovulation was 6.90% with the SDM.
This study highlights that individualized algorithms are advantageous for accurate determination of the fertile window and that static algorithms are more likely to fail during the most fertile days.
Reference: https://www.tandfonline.com/doi/full/10.1080/13625187.2019.1682544
