Effectiveness of the Natural Cycles app demonstrated in clinical studies

In the prospective clinical study of more than 15,000 women with a total exposure time of 7,353 women years, Natural Cycles demonstrated a typical use Pearl Index of 6.5. This means that in total 6.5 women out of 100 women get pregnant during one year of use with Natural Cycles.1

Typical use includes both method failure (i.e. a technicality with the algorithm), and user error (such as having unprotected sex on fertile day).


Contraceptive MethodTypical Use Peal Index
Natural Cycles6.5
Birth Control Pill9
Condom (male)18

¹US Food and Drug Administration. De Novo classification request for Natural Cycles (DEN170052) 2017. https://www.accessdata.fda.gov/cdrh_docs/reviews/DEN170052.pdf