A certification body, Tuv Sud, has approved a fertility tracking device to be marketed as a medical device for contraception in the European Economic Area. In conjunction with a thermometer, the app – called Natural Cycles – uses an algorithm to determine on which days unprotected intercourse would not be advisable.

An industry-sponsored (Natural Cycles Nordic AB) retrospective study published in the European Journal of Contraception and Reproductive Health Care (October 2015) concluded that the app was as effective as the pill, but we were unable to access the full text.

This certainly presents another contraceptive option that is hormone-free and can also conversely be used to plan a pregnancy. Potential negatives include the need to measure body temperature every morning and the need to either abstain from sex or use a barrier contraceptive method correctly on certain days of the month.

A number of fertility experts in the UK have called for large, independently conducted, prospective trials to verify the reliability of such an app.