Can you really rely on a birth control app?

birth control appCC: Bruce Mars at Unsplash

Contraceptive choices have never been so diverse. From patches and rings through to pills and injections, there are lots of options to choose from. Unfortunately, almost all these choices depend on hormonal adjuncts. Some women have adverse side effects and so they may choose to use a birth control app.

Originally designed in Sweden, the Natural Cycles birth control app is 99% effective in lab conditions. This means that for every 100 women who use it correctly, one will fall pregnant. In regular conditions, it’s 93% effective. So, for every 100 women who use it in real life, 7 will fall pregnant.

Although the birth control app comes with the benefit of zero hormones, it also has several flaws. Before you head to your Apple App Store or Google Play to signup, you might want to learn more about it.

How does the birth control app work?

The Natural Cycles birth control app is similar to a period tracker. Unlike a period tracker, it requires you to measure your basal body temperature. By taking your temperature when you first wake and adding the data to the app’s calendar, you should be able to pinpoint when you’re ovulating.


Why does temperature matter? Because women experience a slight drop in basal body temperature when they’re about to ovulate. It will then rise, sharply, as ovulation takes place. For women who are trying to conceive, basal body temperature measurements can prove infinitely useful.

When users sign up for the birth control app they receive a thermometer in the post. They’re instructed to take their temperature as soon as they wake up and enter the information into the app. If the app shows a green circle, they’re good to go on the intercourse front without worrying about falling pregnant. Alternatively, if it’s red, they need to use barrier contraceptives until it’s green again.

As you may have guessed, the birth control app needs to spend a little while calibrating. The designers decided to err on the side of caution and programmed the app to show a red circle with a low index of suspicion during the calibration period. Overall, it sounds safe so far.

The birth control app and human error

While the birth control app may sound safe, it hasn’t proved astonishingly reliable in practice. Unwanted pregnancies have been reported within months of using the app, often among women who didn’t fall pregnant while using oral contraceptives. Although the app has been licensed for use as a contraceptive, that license is now being scrutinised in Sweden. One Swedish hospital reported that 37 out of 688 women who attended there for an abortion were using the Natural Cycles birth control app.

During the app’s development phases, the designers did attempt to trial it in non-laboratory settings. Interestingly, they didn’t subject it to an RCT to ascertain its safety. Instead, users elected to test the app. As is often the case with self-selected trial participants, it’s likely that these users weren’t reflective of your average app user. Had they been so, several human errors could have been highlighted.

True waking time, and shift work

Your basal body temperature is best measured when you first wake from sleep. Depending on your sleep habits, you may find that you wake at 5 am briefly, but then return to sleep until 7 am. If you then measure your basal body temperature at 7 am, you’re not inputting accurate data into the app. This becomes especially problematic if you’re a shift worker who grabs naps mid-shift.

Other reasons for body temperature fluctuations

Illness is a thing, and so if you experience more than one during the calibration period the app may not have a true reflection of what your standard basal body temperature variations are. It’s not difficult to see how poor calibration could lead to errors later on.

Everyday human mistakes

One of the main reasons that taking an oral contraceptive pill isn’t always reliable is that humans aren’t perfect. They may forget to take one, assume they’ve taken one when they haven’t, or they may take one at the wrong time. The birth control app is subject to the same mistakes, except it offers no degree of hormonal coverage you may benefit from.

Overall, there’s no denying that the birth control app could free you from some hormones. But in exchange, you may find yourself experiencing a fresh set for roughly nine months.

About the Author

Laura McKeever
Laura has been a freelance medical writer for eight years. With a BSc in Medical Sciences and an MSc in Physician Assistant Studies, she complements her passion for medical news with real-life experiences. Laura’s most significant experience included writing for international pharmaceutical brands, including GSK.