Mobile applications worldwide bring in an estimated $35 billion in revenue annually. Even still, when the apps concern personal health, they are not as effective as they may seem.

A recent study from Georgetown University researchers has revealed that fertility apps are unsuccessful in helping women avoid or achieve a pregnancy.

After conducting a review of almost 100 fertility apps, most available through iTunes, Google, or Google Play, researchers found that only six fertility apps had perfect accuracy and no false positives.

Lead researcher Dr. Marguerite Duane believes that these apps have become more commonplace for women as a way to have a greater control over whether or not they become pregnant. Even though each app varies in its capabilities, each app generally helps women track their menstrual cycles and allows them to pinpoint when they are ovulating.

These factors are referred to as fertility awareness-based methods (FABMs).

These apps also track a women’s basal body temperature (BBT), the temperature of the body when it is fully at rest. But according to Duane, this is not effective as a rise in BBT happens after ovulation, so it cannot be relied on to achieve accurate results.

In addition, some apps offer birth control services to women and girls as young as 14 years old. With just a few clicks, birth control is delivered to their door, sometimes without a prescription.

Because of the apps’ general unreliability, Duane recommends that women skip downloading them if they’re looking to avoid an unwanted pregnancy.

Duane explains to Medical News Today:

“The effectiveness of fertility awareness-based methods depends on women observing and recording fertility biomarkers and following evidence-based guidelines. Apps offer a convenient way to track fertility biomarkers, but only some employ evidence-based FABMs. When learning how to track your fertility signs, we recommend that women first receive instruction from a trained educator and then look for an app that scored four or more on mean accuracy and authority in our review.”

The study is due to be published in the Journal of the American Board of Family Medicine.