Fertility apps often inaccurate, study shows

People are tracking their own health more and more using mobile health applications and other personal digital health informatics. One such app line involves tracking menstruation and fertility. However, a new study published in the BMJ of Sexual and Reproductive Health in April 2020 throws doubt on the accuracy of these apps.

Image Credit: ADragan / Shutterstock
Image Credit: ADragan / Shutterstock

Why was the study done?

The advantages of using apps to keep track of one’s reproductive cycles include privacy, personal choice, easy availability, and inexpensiveness. It is also thought to help women achieve contraception while avoiding hormonal contraceptives if desired. It is estimated that such apps have been used to track periods with at least 200 million downloads until the year 2016.

These apps are not free of controversy, however, despite their perceived benefits. For one, they are often marketed by dubious means. Secondly, the evidence for their utility and effectiveness is in question. The current review was motivated by the need to pull together current knowledge about these self-tracking platforms.

How was the study done?

The authors selected 18 papers that met the inclusion criteria. Seven of them came from the US and others from various other countries. The apps described were sorted into three classes: those used to track fertility and reproductive health, to plan pregnancy, and to prevent pregnancy.

One in three papers dealt with self-tracking apps for fertility and reproductive health. Three of these papers discussed why women want this type of tracking and found four chief reasons:

  • Observing their cycle – 72%. Self-observation was itself carried out either to understand their own bodies better or to get to know how their bodies responded to the changing phases of the reproductive cycle.
  • Conception
  • Part of fertility treatment
  • Contraception

Menstruation trackers

One study on menstruation trackers confirmed the above motivations. It also suggested that if the app allowed women to record a number of symptoms, such as the date of menstruation, cervical mucus, basal body temperature, fluctuations in mood, and so on, the women tended to become less regular and more inaccurate in their recording – which could be attributed to ‘tracker fatigue’.

While this could be true of all methods to self-track fertility, it is important to note that inaccurate and inconsistent recording negatively affects the accuracy. This could result in conception, for instance, if the purpose of the tracking was to prevent pregnancy by predicting their fertile days. This is one example when the accuracy that is desperately needed is itself sabotaged by the need to input too much data.

On the other hand, the authors also note that even women who were tracking for the sake of observing their own reproductive health desired accuracy. And moreover, the motivations with which women begin to use such apps may vary with time and the period of life rather than remaining static.

An interesting study focused on the use of an app used largely in developing countries, based solely on the first day of menstruation, and which helped to plan or prevent pregnancy, and to observe the cycle. With only one input, the algorithms predicted the fertile days. Most users in low- and middle-income countries were 20-39 years old, and 40% used it for contraceptive purposes, while an almost equal number were planning their pregnancy. Of the 22% tracking their cycles, a third were not on contraception for 3 or more months prior to its use. This app seems to be an inexpensive method to make fertility planning awareness more widespread and facilitate reproductive intentions of various kinds in such regions. Tracking apps can also yield data that can be used to enhance women’s health.

Pregnancy planning

One paper focused on a particular app used in Japan to plan pregnancy as part of a commercial health service for women. The authors argue that the need to enter only the first day of menstruation makes it ideal for couples who are beginning to plan pregnancy. They point out that data recording must be consistent for a good prediction of the fertile days, but that the large size of the database makes it capable of more accurate prediction.

Another paper showed that only 9% of the top 33 free fertility apps for mobile phones actually were accurate in their prediction of the fertile window, or did not falsely classify fertile days as infertile. Another larger study on 108 free apps found only 20% to be accurate. The authors commented that most of these free apps are “inaccurate, containing misleading health information, or do not function.” This is important because 80% of these apps were meant to help plan a pregnancy and 50% of avoid it.

“The ability to accurately predict the fertile window is important, but the limited research that exists seems to indicate that many of the most popular apps are not accurate, even though they might contain information that supports pregnancy planning or are marketed specifically for this purpose,” write the authors.


Over half of the papers cover the use of apps to prevent pregnancy. Some use both the first day of menstruation and the basal body temperature to predict the fertile window. Others use only the first day of menstruation. Some of the authors argue for the greater inclusion of women’s health specialists and consumer groups while designing apps to give women the power to decide which apps to use.

Duane et al. found in their study that most fertility apps that are marketed as contraceptive apps are neither designed to support this aim nor do they use fertility-based awareness methods built on sound evidence. This could lead to unintended pregnancy.

What does this study show?

While women value apps that provide accurate and relevant information about their reproductive cycles and fertility, there’s little evidence to show that most apps do fulfil their purpose. Very few have gained FDA or European approval. The way these apps are marketed is often unsatisfactory.

The current study authors say, “Existing apps do not necessarily take into account the way in which women use such apps and human-computer interaction researchers highlight the importance of involving users in their design and development. This is especially important because the user is considered to be the single greatest ‘risk factor’ in the accuracy of apps.”

However, the researchers suggest a standard for future app approvals, and the inclusion of fertility specialists in the development process to make sure the apps are suitable for a range of needs over a spectrum of ages. Developing countries should take advantage of such apps to track the fertile period in a cost-effective manner.

Apps risky for contraception

During the current pandemic, many women may use such apps to avoid pregnancy. However, with the lack of evidence as to their accuracy, using fertility apps to achieve reliable contraception is a risky affair. Diana Mansour of the Faculty of Sexual and Reproductive Healthcare (FSRH) recommends, “If women need to start contraception or get a repeat prescription during the COVID-19 pandemic, I advise them to call their GP or contraceptive clinic to discuss their need. Most GP practices will be able to issue an electronic prescription that women can collect in their nearby pharmacy; other services can supply/post their preferred method.”

Journal reference:
Dr. Liji Thomas

Written by

Dr. Liji Thomas

Dr. Liji Thomas is an OB-GYN, who graduated from the Government Medical College, University of Calicut, Kerala, in 2001. Liji practiced as a full-time consultant in obstetrics/gynecology in a private hospital for a few years following her graduation. She has counseled hundreds of patients facing issues from pregnancy-related problems and infertility, and has been in charge of over 2,000 deliveries, striving always to achieve a normal delivery rather than operative.


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