Choosing the best fertility app and basal body thermometer

So you want to chart your cycles for natural birth control?

The fertility awareness method is a practice of charting your fertility biomarkers, or your ovulation signs, to identify when in the cycle you’re fertile and when you’re infertile.

The cool thing about FAM is that you’re making observations, recording the data, and then using that information to make decisions! If you want to use FAM effectively, you’ll need a few things to keep track and interpret that ovulation data.

With the boom of femtech, and dozens of fertility apps available on the app store, how do you choose which app and thermometer to use?

apps like daysy or natural cycles

To start, you might have gotten an ad for a thermometer or device like Natural Cycles or Daysy, and are wondering if those work just as well as learning a method of FAM.

If you have very regular cycles and you would be open to a pregnancy, these apps and devices are a great way to dip your toe into the world of FAM.

However, if you’re strictly avoiding pregnancy, I wouldn’t recommend them. Here’s why:

They rely only on temperature which is a retrospective marker of ovulation. What happens if you were to ovulate earlier than your algorithm predicted? You would miss the signs of cervical mucus as estrogen rises, leading to a potential unintended pregnancy.
Their algorithms don't take into account cervical mucus to open the fertile window. Cervical mucus is the only marker that we can rely on for accurate, real-time information about our fertility. An algorithm cannot predict ovulation, but cervical mucus gives us real time info about our estrogen levels that an algorithm can't interpret.
They are risky, not relying on the conservative rules that are recognized by fertility awareness based methods. Daysy and Natural Cycles will mark you as safe after a withdrawal bleed which is incredibly risky as you can ovulate immediately after a withdrawal bleed.
They are downright inaccurate, in some cases indicating a a temp shift when there never was one.
They’re expensive or rely on a recurring subscription.
They take the autonomy and body literacy out of fertility charting, forcing you to rely on an algorithm without you understanding how to interpret your charts. If you don’t have internet connection or if your subscription runs out, how will you fill the gaps if you don’t know how the method is actually working?

period tracking apps

Apps with built in fertile window or ovulation predictions, whether they’re marketed as contraception or not, are also relying on a guess to open your fertile window or let you know you’re ovulating.

The difference between an in depth method of fertility awareness and a period tracking app, is that with FAM, you’re tracking ovulation in real time.

Do yourself a favour and ignore these predictions or find another app. They’re often inaccurate and these apps usually won’t let you manually mark coverline, peak day and temp shift (a great FAM app lets you manually put this in).

People like to have the confidence in FAM and hope that a device will back them up or eliminate the user error with FAM, and these apps and devices are capitalizing on this.

If you choose to learn FAM, you’ll find that it’s easy it is to be your own algorithm and rely on your own knowledge of your body in order for the method to work.

what to look for in an app

The ability to mark your own Coverline, peak day, and temperature shift.
The ability to turn ovulation or period prediction off.
The app doesn’t claim to evaluate your fertility or give you a window/percentage of fertility each day.
Basically, you want an app that resembles a paper chart but on your phone (and if you’d rather just use a paper chart, you can download one here).

Apps I recommend:

Read Your Body is a fantastic “paper chart on your phone” app that is fully customizable and syncs with Tempdrop.

Lutea is a free app, that also functions as a “paper chart on your phone.”

what about thermometers?

If you’re using a Symptothermal method of fertility awareness, you’ll need a basal body thermometer to track this ovulation sign.

Look for a BBT that:

Goes to 2 decimal places.
Allows you to read the temperature right off the thermometer, rather than needing to sync to an app in order to read it.
Handy features, but not entirely necessary are: backlight (so you can read the reading bleary eyed early in the morning), a temperature recall feature.
Requires you to interpret your raw temperature and input it into your own fertility chart to read alongside your other biomarkers, such as cervical mucus.

Check out some of my favourite thermometers and other charting tools.

with FAM, your body is your birth control

These tools allow you to observe your fertility signs, so you can identify your fertile and infertile times of the cycle. With that knowledge, your body is your birth control!

Next, you’ll need a method to help you interpret those signs and give you the rules for when you’re safe to go unprotected.