Effectiveness of the Natural Cycles app demonstrated in clinical studies

Several clinical studies have been conducted to evaluate the real world effectiveness of the Natural Cycles app for contraception.1–3 These studies have shown that the contraceptive effectiveness of Natural Cycles is comparable to that of oral contraceptives, and is an improvement on the effectiveness of traditional fertility awareness methods.1,2,4

 

Typical-use effectiveness of 93%

The Natural Cycles medical app for contraception has a typical-use effectiveness of 93% (1-year Pearl Index of 6.8 [95% CI: 6.4–7.2] pregnancies per 100 woman-years). This means that on average, 7 out of 100 women will become pregnant over one year of use for a variety of reasons (e.g. unprotected intercourse on red days, or failure of the contraceptive method used on red days).1

 

Perfect-use effectiveness of 99%

The Natural Cycles medical app for contraception has a perfect-use effectiveness of 99% (Pearl Index of 1.0 [95% CI: 0.5–1.5] pregnancies per 100 woman-years). This means that on average 1 out of 100 women who use the app for one year and who become pregnant will do so either due to:

 

  1. Unprotected intercourse on a day that was falsely attributed as green and non-fertile (i.e. method failure); or
  2. Protected intercourse on a red day, but the chosen method of contraception failed.1

 

The perfect and typical-use effectiveness data are based on the results of a prospective, observational, clinical study on contraceptive effectiveness involving 22,785 women using the app for an average of 9.8 months. The results of this study were published in a peer-reviewed journal.¹

Comparison of Natural Cycles app with other, commonly used short-acting contraceptive methods1,4

 

Contraceptive Method% of women experiencing an unintended pregnancy within the first year of use% of women continuing use at one year
Typical usePerfect use
Natural Cycles7146
Traditional* fertility awareness-based methods240.4–547
Male condom18243
Combined pill and progestin-only pill90.367
*Non-digital, manual analysis methods

¹Berglund Scherwitzl, E., Lundberg, O., Kopp Kallner, H., Gemzell Danielsson, K., Trussell, J., & Scherwitzl, R. Perfect-use and typical-use Pearl Index of a contraceptive mobile app. Contraception. 2017;96(6):420–425.
²Berglund Scherwitzl E, Gemzell Danielsson K, Sellberg J, Scherwitzl R. Fertility awareness-based mobile application for contraception. The European Journal of Contraception & Reproductive Health Care. 2016;21(3):234-241.
³Berglund Scherwitzl E, Lindén Hirschberg A, Scherwitzl R. Identification and prediction of the fertile window using NaturalCycles. The European Journal of Contraception & Reproductive Health Care. 2015;20(5):403-408.
4Trussell J. Contraceptive failure in the United States. Contraception. 2011;83(5):397-404;

 

Read more