The use of smartphone apps to track period and fertility

October 19, 2019

Women are increasingly turning to smartphone apps to track everything from their periods to their fertility. There is a multitude of such apps available, which only demonstrates how popular they’ve become in recent years. New technologies, and in particular self-tracking, are changing the way we perceive our bodies and health. Both users and doctors wonder about the opportunities and the usefulness of digital self-tracking. While these measurements and observations are noisy and not perfectly regular, they provide valuable information for inferring the underlying hormonal changes and timing of ovulation. This digital epidemiology approach can help lead to a better understanding of menstrual health and its connection to women’s health overall, which has historically been severely under-studied.

One of the most popular apps comes from Natural Cycles, a Swedish company. Some women use the app to track their periods to determine fertile windows, others to track times that conception is less likely, and still others simply want to be informed over their reproductive cycle. The app requires women to take their body temperature with a thermometer daily. Then, an algorithm uses that data to predict the days when they might ovulate so the information can be used for pregnancy planning or contraception. It is a non-hormonal contraception option, which is an attractive choice for women who have had unwanted side effects from using other methods of contraception.

Fertility apps like the Natural Cycles app can be a good method of contraception to some women, however there are a few things to consider before deciding on whether to use it (others like it). In January 2018, complaints from 37 Swedish women who got pregnant while using Natural Cycles raised concerns about the product’s effectiveness and reliability as a contraceptive. Currently, the failure rate of the app is 7%, meaning that with ‘typical use’ 7 out of 100 women are likely to get pregnant when using the app. ‘Typical use’ refers to how the general population, rather than people in a clinical trial, would use the app. It accounts for errors like taking temperature at a different time than usual or having unprotected sex on a day when the app suggests abstaining or using another method of contraception as additional protection.

Fertility apps like the Natural Cycles app can be a reasonable option for motivated women with regular menstrual cycles that strongly wish to avoid other forms of contraception and for whom a pregnancy wouldn’t be the end of the world. If a woman absolutely does not want to get pregnant, another method of contraception should be used in conjunction with the app. Furthermore, for women that do not want to be restricted in when they can and cannot have intercourse this would not be a good option. Women who have a medical condition where pregnancy would be associated with a significant risk to the mother or the fetus are not advised to use such apps. Before making a choice about using these apps it is advised to speak to a doctor. Another obvious disadvantage of such apps is that they do not protect against sexually transmitted infections in the same way as a condom.

However, all that said, fertility apps are trying to blend technology with fertility tracking to empower women with knowledge about their own reproductive biology, which is, of course, always beneficial. Finally, the widespread use of mobile phone apps for personal health monitoring is generating large amounts of data on the menstrual cycle. Provided that the real-world data can be validated against traditional clinical studies done in controlled settings, there is enormous potential to uncover new scientific discoveries in this understudied area.



  1. LSymul, KWac, P Hillard, M Salath. (2019). Assessment of menstrual health status and evolution through mobile apps for fertility awareness.Digital Medicine; 2 (1) DOI: 10.1038/s41746-019-0139-4
  2. M Duane, A Contreras, E T Jensen, A White. (2016). The performance of fertility awareness-based method apps marketed to avoid pregnancy. The Journal of American Board of Family Medicine; 29 (4) 508-511. DOI:10.3122/jabfm.2016.04.160022


For more information about the different types of contraception available and where to find them:


If you are currently experiencing an unplanned pregnancy and considering abortion you are not alone. Abortion is available for free to those part of the NHS but can also be paid for privately. For more information:


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