The fertility tracking app Natural Cycles has once again hit headlines. The Advertising Standards Authority banned its adverts, saying that claims implied that it was ‘a precise and reliable method of preventing pregnancies which could be used in place of other established birth control methods’ (Wakefield, 2018).
The app, although a recent development, is based on the rhythm method, which of course is not new at all. Women take their temperature at the same time each morning, preferably before sitting up, and log it via the app, which uses readings to predict when a woman will be fertile. Natural Cycles claims a 99% efficacy rate (Morley, 2018) and became the first and only app to be approved as a contraceptive by the US Food and Drug Administration and the EU.
Since then, however, stories have emerged of women becoming pregnant after using the app (Sudjic, 2018; Foster, 2018), and developers have been forced to clarify its efficacy after a study found that 7 women in 100 would become pregnant with typical use—not 5 in 1000 as previously claimed (NHS, 2016). In addition, developers have explained that the ideal user is in fact a woman in a stable relationship who is planning to have children and would like to ease herself off hormonal contraception (Lundin, 2016). The temperature recording is hypersensitive, affected not just by travel or shift work; but also by fever, late nights or any kind of insomnia or temperature change (Foster, 2018) (the recent UK heatwave must have produced some pretty interesting readings). Natural Cycles also relies on women (who can download the app without consulting a health professional) evaluating its suitability and using it correctly, with little room for error.
Nevertheless, estimates suggest that Natural Cycles has more than 300 000 users (Wakefield, 2018), so what has it got right? Its developers recognised a real demand for hormone-free contraceptives, since many women can point to a litany of adverse side effects that they or their friends have experienced (Foster, 2018). Developers also recognised that women value control and informed choice over their bodies, and that these women are busy: they use their smartphones to organise and inform many other aspects of their lives, so the convenience, ease and discretion of a contraceptive app is not to be ignored.
As a result of the increasing use of smartphones, we will certainly see more health apps in future, and there are many lessons that can be learned from Natural Cycles. Smartphone apps provide informed choice via a medium that is familiar and readily accessed; however, there can be no assumptions made about the likelihood of perfect use, given users' busy lives. Natural Cycles therefore exemplifies how technological healthcare interventions are all grappling with the same problem: users may want control over monitoring their health, but developers should recognise that convenience and lifestyle constraints may win out.