What’s new about the Natural Cycles app?

Dear Cyclers,

You can now download the new updated version of the Natural Cycles app. We worked really hard to improve it and listened to all of your valuable feedback. We’re super excited and proud of it, and we hope you’ll like it as much as we do!

Along with the major design changes, we have even more news! Natural Cycles is now available on Apple Watch, and the Natural Cycles algorithm has been updated to even more accurately find and narrow down your fertile window.


Track your Fertility mode

Safety is our number one priority and it was therefore important to make sure that the new design reflects what’s most important about Natural Cycles.

  • The focus in the new app is on today’s fertility status – red or green.  Simple!
  • Below your current fertility state, you can see your predictions for the week. Here, it was very important to make clear that predictions may change in the future and should not be taken for granted – just like with the weather.
  • After today’s current view, you can switch to have a monthly overview presented to you as a calendar. Here again, it was very important to separate your past fertility from future predictions.
  • If you want to dig a little deeper into your data, you can have a look at the graph as well as your cycle statistics.


The new design is a result of several thousands of hours listening, analyzing and engaging with your feedback. Thank you!


Below, you will find an explanation of the icons as well as some answers to most common questions.


prevent overview


How to enter data


To enter your daily data, click on the + in the upper right corner. Enter your temperature and if you want to add any additional data, such as ovulation test result or a note, you click on “additional data”.  Click ‘save’ and you’re all set! In this view you can also swipe to the left to go back in time to see your previously entered data. If you have entered any data and then swipe back, your data will be saved automatically!


How to access the graph?

the graph view

You can access your graph under the “today” view by tapping on the graph symbol in the upper right corner – we are currently working on further improving the graph, so stay tuned!



Changes in the algorithm

With significantly more data from all you Cyclers, we were able to optimize our algorithm for the new app such that it will identify and predict ovulation and your fertile window with even greater accuracy. This update in algorithm might lead to small changes in the history of your data, which means that you might see a previously red day change into a green day, and vice versa. This is normal because we run a new, improved algorithm over your entire dataset. You do not need to worry about this – important is to always check today’s fertility status!


Natural Cycles Plan mode


For Natural Cycles Plan users, we focused on clearly highlighting your most fertile days. The most fertile days are indicated in red, while your less fertile days will be shown in different shades of soft pink colors. Your non-fertile days are shown in  a light grey color.
overview plan

We’re excited to hear your feedback,


All the best,
The Natural Cycles Team

How the Natural Cycles algorithm works

Today’s blog is about how the Natural Cycles’ algorithm works, aiming to answer questions like why upcoming fertility predictions can vary and why ovulation day can differ from one cycle to another.  We also wanted to give our Cycler’s an exclusive sneak peek at the new app interface that will be released later this year. Please let us know your thoughts!


The Basics

The Natural Cycles’ algorithm works by calculating your fertility based on the temperature readings and LH tests you enter into the app from the very first measurement up to the most recent.


Both the weekly and monthly forecast’s found on the calendar view are fertility predictions (indicated by question marks and hollow circles) that are completely tailored to each individual, mapping your unique cycle and important events, like ovulation, with the highest precision possible from the data you have already entered into the app.


However, like all predictions, your upcoming fertility can change as unfortunately we cannot see into the future!  With every new data entry, the app’s algorithm adapts and adjusts accordingly to help paint the clearest picture of what you can expect in the days to come.  This is why we always say check your fertility status each day – especially around ovulation – as it can differ from what was forecasted the week before!



In this calendar, ovulation day is predicted on Wednesday but according to the data you enter the exact day can vary. Once ovulation is detected it will be indicated with a blue egg icon on a complete red circle.


Data entry and cycle variations


A key determining factor for forecast variations is data entry.  The more data a Cycler enters the better the algorithm can be at determining your cycle’s usual pattern and thus predict what is coming up. So gentle words of encouragement – try and measure as much as possible to improve your data!


Cycle variations, such as a delayed ovulation day can be another reason for changes in your calendar. Cycler safety or their success is our priority so if the app detects something unusual it adapts by either a) giving more red days to be sure you’re protected from the risk of pregnancy (prevent) or b) advises you to keep trying as you’re likely to be highly fertile (plan), respectively.


Below is the in-app notification for Prevent users that will pop up if your ovulation is delayed.


Screen Shot 2015-10-08 at 16.30.09


Alternatively, for Plan users this  in-app notification will be displayed if your ovulation day is delayed. 


Screen Shot 2015-10-09 at 15.37.27


Cycle variations are common as the follicular phase (before ovulation) often varies in length. For instance, if you ovulated on day 18 on your previous cycle, it doesn’t mean that you will this cycle or even next.


A Cycler will only get green days once it is clear you have ovulated (with a clear rise in temperature) and is confirmed by the app. The app confirms this with a blue egg icon on a filled red circle on the calendar view or a blue egg icon and blue line seen on the chart/graph (see below).


Ovulation day was confirmed on cycle day 16 indicated by a blue egg icon and blue line on the chart/graph view.

Chart/graph view: Ovulation day was confirmed on cycle day 16 (CD16) indicated by a blue egg icon and blue line.


Ovulation day has changed


A couple of observant Cyclers have noticed that when looking back at their previous cycle their ovulation day has changed by a day or so. This is because the algorithm is constantly trying to calculate the exact day of ovulation even after it has already happened! Once your luteal phase has ended, which is indicated by the start of your period, the app has more information to work from.  With this extra bit of information, the app really does know when you ovulated and uses this to create an even more accurate picture of when you will ovulate this next cycle.


You can see that the app is continuously working very hard to get to know your cycles – variations and all! Natural Cycles adaptability to women’s cycles no matter what shape or size they are – long, short, irregular – is what makes it suitable for almost anyone. You can be assured you are always protected.


How will the new app differ?


The new app, that will be released later this year, will be even more intuitive and easier to follow. You can see below that it has been designed so that your fertility for the day is the core focus.


The upcoming fertility predictions will only be visible if you request to see them via the ‘Tap to show’ button. This way we can ensure that you feel confident about your actual fertility status instead of relying on predictions that may change.










Let us know what you think?

The Natural Cycles Team



How do I use my NaturalCycles Statistics?

When using NaturalCycles for the first time you might ask yourself “How do I use my NaturalCycles Statistics?”, especially when you’re new to terms such as luteal phase and your statistics are looking a bit incomplete.


No numbers yet to be shown!


But after measuring for sometime (usually after 1-2 cycles) and after NaturalCycles has detected your ovulation day, you can expect your statistics to look a little more like this:

Screenshot 2015-04-23 15.29.30

Below you can read what all the signs/numbers mean. (Click on the picture to make it bigger)

Let us know if any questions come to mind – email us at support@naturalcycles.com



Your Cycles Statistics!

Everything you need to know about the Natural Cycles basal thermometer

To get started with Natural Cycles you will need a basal thermometer. It’s more sensitive than a regular fever thermometer as it shows two decimals.

Here are the most useful tips on how and when to measure your temperature with it:

basal thermometer, naturalcycles, natural cycles

The basal thermometer!

Why Basal Thermometer?

A basal thermometer is a digital thermometer showing two decimals, (for example 36.99). It is much more sensitive than a regular thermometer, as it measures the slightest changes in your temperature. Something that is very important when measuring your basal body temperature, which rises in very small amounts near ovulation.

When to measure?

Measure first thing in the morning, even before you get out of bed! Why? The basal body temperature is our resting temperature and is lowest when we sleep. The slightest movement (getting out of bed) will increase your body temperature, thus making your reading further away from your actual basal temperature and therefore slightly less accurate. In fact, we advise NaturalCycle users to try and measure at roughly the same time every day, within a ±2 hr window of your usual morning alarm. If you decide to have a lie-in after a busy week at work then we suggest you leave it for the day.

How to measure?

howtomeasure, naturalcycles, thermometer, basal 

I’ve measured twice and thermometer shows two different temperatures?

Our basal thermometer’s are super sensitive in order to capture the minute changes in your temperature. With every reading your body’s temperature will naturally rise, and so the first reading is likely to come out lower than the next. There is no need to measure twice as the first reading will be the closest to your actual resting temperature.

What is LO?


‘Lo’ means low temperature, and not low battery – so no worries! The reason it says ‘Lo’ from time-to-time is because room temperature is roughly 21 degrees, which is ‘Lo’ for our basal thermometer. Body temperature should be around 36.5–37.5 degrees (a little science for you). Any higher than this, then you probably have a fever and therefore advise you to leave the reading for the day.

A big pointer for all you newbies! It will take a 1-3 cycles of measuring for Natural Cycles to get to know your unique cycle.



Your Natural Cycles team


Optimized algorithm = more green days!

Exciting news! NaturalCycles has further optimized the algorithm with all the awesome new data streaming in on a daily basis.

Thanks to more than 40 000 days of collected data we are now giving 10% more green while remaining 99.9% safe. You can now see the new results in both your fertility history and the predicted red and green days.

Check it out in your app (AppStore / GooglePlay) or on your MyCycles page.


Optimized algorithm

Newly designed NaturalCycles app for iOS in App Store!

The newly designed NaturalCycles app for iPhone and iPad is now approved and in the App Store. Update your apps or download it for free here!


You get a three month free Plan/Prevent trial.

Newly designed NaturalCycles app for iOS

NaturalCycles iOS App submitted

Hi everyone!

Today we finally submitted our NaturalCycles iOS app for approval for being released for iPhones and iPads in the Apple Store.

The procedure to submit an app to Apple is quite extensive, with many configurations to set and certificates to create. That’s why we are so happy today that we’ve completed all of this work, which not to forget also includes developing the app itself. Now comes the real review process on the Apple side, which can take up to 6 weeks.

Our app has the same structure as the NaturalCycles website for the logged in user – it is different for NC Free, Prevention and Planning. The app itself is free, but one needs to register for a NaturalCycles account to use it, either on the app itself or on NaturalCycles.com. Similar to our website, the whole app changes its color scheme depending on whether you are having a red (fertile) or green (not fertile) day or if you are pregnant, which is when everything becomes blue.

iOS App - NaturalCycles

iOS App - NaturalCycles

iOS App - NaturalCycles

iOS App - NaturalCycles

In addition to the fertility calendar and temperature chart, the app also has the analytics summary of your cycle and a pregnancy tracker if you are pregnant. It also contains Prevention and Planning discussion forums, where you can chat with other users and share your charts, etc.

I think the app is a very nice addition to our website, since NaturalCycles is something you use on a daily basis and not everyone sits in front of a computer all the time, like I do. The app is made with a cross-browser framework called PhoneGap, such that it works for all device dimensions and should be easy to duplicate also to other platforms. Hopefully the Android app will not come long after the iOS app.

When to measure and when not to measure

One question about tracking the basal body temperature for natural family planning is when to refrain from measuring. If you are clearly sick and have a fever, NaturalCycles will detect your temperatures as abnormal and automatically exclude them. However, if you are just feeling slightly under the weather, or have been partying the day before, or simply sleeping significantly more or less than usual, your temperature measurement for that morning could be slightly shifted. This is not at all “dangerous” and it will not make you get green days during your fertile window. It could however cause you to get less green days as NaturalCycles provides the same level of safety for all types of temperature fluctuations.

It is therefore better to refrain from measuring for days where you don’t follow your normal rhythm. Especially if you haven’t just started measuring your temperature. NaturalCycles uses all of your data data from the first cycle you enter, when it analyses your new incoming temperatures and therefore, after three cycles or so, statistics become less crucial. Myself, I have now used NaturalCycles for 500 days and I have meanwhile acquired quite some statistics. I therefore only measure on days where everything is according to my normal every day schedule. For example, before this morning (Monday), I did not measure since Wednesday (see chart). Thursday was the Swiss national holiday so there was some drinking involved for both Wednesday and Thursday evening. Then, during the weekend, I slept considerably longer than usually. Since my data are not limited by statistics anymore, and I am not yet close to ovulation, it is fine for me to skip those 4 days in a row. I you have a look at my chart below you see that there is a nice line until today, probably since I skipped the days before where I’d otherwise get elevated temperatures due to sleeping in/alcohol.

Measures - NaturalCycles

I will summarize some useful rules of thumb that you could adopt for optimal temperature tracking:

  • For the first 3 cycles, try to measure as often as possible
  • For the 5 days before and after expected ovulation, try to measure almost every day
  • Outside these two scopes try to at least measure 4 mornings/week, but strictly don’t measure if:
    1. You get more than 2 hours of more/less sleep than usual
    2. You wake up more than 3 hours earlier/later than usual
    3. You drank more than usual the evening before and you feel the alcohol the following morning
    4. Skip the first morning after having traveled long distance to a different time zone
    5. You feel ill or have a fever

If you apply these guidelines, you should get nice temperature curves. There will of course always be some fluctuations, which cannot be avoided, but that’s normal and nothing to be concerned about. You should also try to avoid first measuring and then deciding whether to use the temperature value or not. That might bias your chart to look like you want it to, rather than what is actually correct.

When you have to measure the LH hormones with ovulation tests (OPKs), you don’t have to worry about more/less sleep or alcohol.

You should however try to not drink any liquids and not go to the bathroom at least 2 hours before measuring, preferentially more than 4 hours. Best is also to avoid taking the test in the morning. This might sound confusing, as pregnancy tests are best taken when you wake up, but the LH surge often starts in the morning, so if you take your ovulation test then you are more likely to miss your LH peak. Of course, if you don’t find a good time during the day to avoid liquids for a longer time, then the morning is to be preferred.

Happy measuring!