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.
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 Method||Typical Use Peal Index|
|Birth Control Pill||9|