Natural Cycles has become the first fertility app to be approved as a contraceptive in Europe. Its CE marking of class IIb signifies that it has met safety, health and efficacy requirements in the same risk category as a condom.
The app is based on natural family planning methods that existed long before smartphone apps ever did, but Natural Cycles modernizes those tracking methods by combining readings from a basal thermometer with a proprietary algorithm that accounts for cycle irregularities and sperm survival rates. It presents information in a mobile interface that denotes which days the user is not fertile and which days she should use protection.
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One study of 317 women showed that the Natural Cycles algorithm was able to identify ovulation with near-ultrasound level accuracy. Another study, which was performed on over 4,000 women, showed that an average of seven women out of 100 became pregnant in a year when using Natural Cycles as a birth control method. Both studies were published in The European Journal of Contraception & Reproductive Health Care.
This is equivalent to a typical use Pearl Index (a measurement used in clinical settings to denote birth control efficacy) of 7.0. For reference's sake, traditional natural family planning is usually considered to have a typical use Pearl Index of 25. Typical use Pearl Index for the pill is usually reported around 9.
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