An app that tells women when it is safe to have unprotected sex has been found to be as effective at preventing pregnancies as the contraceptive pill.
Natural Cycles, which is used by 380,000 women worldwide as a form of birth control, uses artificial intelligence to predict the six fertile days in each menstrual cycle.
The largest-ever study into its effectiveness found it was 99 per cent effective under “perfect” use and 93 per cent effective under “typical” use - compared with 91 per cent for the pill.
The app, which costs £40 a year, uses dates of menstruation, sexual activity and body temperature to inform couples when they need to take precautions to avoid pregnancies.
A study of 22,785 women, with an average age of 29, found 6.9 per cent became pregnant within a year.
Professor Kristina Gemzell Danielsson, of the Karolinska Institute in Sweden, said: “Since more and more women are choosing natural contraception as an option, we welcome that there is a certified app with solid clinical evidence.”
The study was published in the journal Contraception.