Frequently Asked Questions

Read up on the questions we get asked the most.

To use the app you will need a basal thermometer. Basal thermometers are more sensitive than regular fever thermometers as they show two decimals (e.g. 36.72°C / 98.11°F). The amount your temperature changes is quite small, so to get the most out of Natural Cycles and receive more green days you will need the correct thermometer. The good news is that you get one included when you sign up for our “annual subscription”.

The Natural Cycles algorithm adapts to your unique cycle pattern by learning over time as you add more data. When you start using Natural Cycles, it can take some time to get to know your unique cycle, resulting in an increased number of red days in the beginning. The increase in the number of red days is to ensure that the app is effective, but once it has detected your ovulation you are likely to receive more green days. If you have a regular cycle, a steady temperature (without many deviating entries) and enter measurement data regularly (at least 5 days a week), then you can expect to get around 60% green days after three months of using Natural Cycles.

Your temperature will deviate if you feel sick, hungover, have slept more or less (±2 hours) than usual or are travelling across different time zones or climates. Under these circumstances do not measure your temperature that day – then tap ‘Skip today’ – or mark the entry as a ‘Deviating temperature’ in the Add Data view. This way the measurement will not be used in the algorithm’s calculation. The app will still work effectively, but you might get a few more red days. Please read the Instructions for Use thoroughly as this contains all the information you will need to use Natural Cycles effectively.

The number of red days varies Cycler to Cycler as every woman is different so there is no set number of guaranteed red days. It depends on the regularity of your menstrual cycle and how regularly you input data into the app, as well as having a steady temperature. Have patience and give the algorithm time to learn about your body, after three months you should see the number of red days decrease. You and your partner should be comfortable with abstaining from sex or using protection on red days to prevent a pregnancy.

It depends on the type of birth control you are using. If you are using non-hormonal birth control (e.g. condoms), you can get started right away. Hormonal birth control affects your cycle and temperature, so you cannot start using Natural Cycles until you have come off it.

If you are using the pill, we recommend you finish the pills in the packet, you can start using Natural Cycles as soon as you have done this. Please keep in mind you will have a high number of red days in the beginning, but this will improve over time.

With both the IUD and the birth control implant you should wait until the day after these have been removed to begin using Natural Cycles. The demo mode is safe to use until this point and will help familiarize you with digital birth control.

Again, Natural Cycles can be used the day after removal of the hormonal patch and the hormonal birth control ring. Remember there will be more red days in the beginning.

If you’re using the birth control injection then you should wait 8-13 weeks for the effect of the injection to have worn off before you can start using Natural Cycles. Depending on the type of injection the timeframe can vary so speak to your gynaecologist if you are unsure.

Natural Cycles may be suitable for women who are looking for an effective,* natural method of contraception and have a lifestyle that enables them to take their temperature first thing most mornings. It is very important that women who want to use Natural Cycles feel comfortable using protection (such as condoms) or abstaining from sex on red days. Using Natural Cycles does require a level of commitment, so the better it suits your lifestyle, the more you will get out of it.

*Natural Cycles is 93% effective with typical use. This means that in a year of use, an average of 7 women out of 100 will get pregnant while using Natural Cycles.

If you have irregular menstrual cycles (i.e. cycles lasting fewer than 21 days or greater than 35 days in length), Natural Cycles may be a less suitable choice of contraception for you. This also applies to users with fluctuating temperatures as predicting fertility is more difficult under these circumstances. Natural Cycles can still be used if you have irregular cycles or an overly varying temperature, but it’s important to remember that you will likely experience a higher number of red days. With this in mind, please consider that you may be less satisfied with Natural Cycles as a means of contraception.

Once you have ordered your thermometer you can expect the following shipping times:

Up to six days for Sweden and the UK. Up to 11 days for the rest of Europe and the US (except Alaska and Hawaii). Up to 22 days for Brazil. Up to 30 days for the rest of the world.

You can order your thermometer in Celsius or Fahrenheit.

We ship thermometers all around the world except to the countries of Mexico, Argentina, Colombia, South Africa, Saudi Arabia, United Arab Emirates, and Chile. You can, however, get your own two decimal certified thermometer and use it in conjunction with the Natural Cycles app.

It’s important to note that Prevent Mode is only approved for use in Europe and the U.S. residents of other countries should use Natural Cycles for planning a pregnancy only.

The effectiveness of Natural Cycles is supported by clinical evidence, which shows a typical use effectiveness rate of 93%. Typical use effectiveness takes into account all possible reasons for becoming pregnant while using the app: from having unprotected sex on a red day to the app wrongly attributing a green day or the chosen method of contraception on a red day having failed.
This means that Natural Cycles is less effective than the IUD, but in the same effectiveness category as the pill.

It is important to note that the effectiveness of Natural Cycles relies on you and your partner using protection (e.g. condoms) or abstaining from sex on red days.

Before you get started, read the Instructions for Use thoroughly as this contains all the information you will need to use Natural Cycles effectively.

Natural Cycles is an app you can download from the App Store or on Google Play. You can start using the app by purchasing a “Monthly or Annual Subscription”. The annual subscription includes a two decimal basal thermometer, which you will need to be able to use Natural Cycles. A basal thermometer is more sensitive than a regular fever thermometer.

Both subscriptions will renew automatically unless cancelled. You can cancel, renew or change payment type at any stage in your “Profile” within the app. If you have purchased via in-app purchases go to your iTunes settings. Please note that with the “annual subscription” payment and you will be charged in full for 12 months of access to Natural Cycles.

Before you get started, read the Instructions for Use thoroughly as this contains all the information you will need to use Natural Cycles effectively.

During your menstrual cycle your temperature rises and falls slightly which is due to the change in your body’s hormone levels. So the Natural Cycles algorithm analyses your temperature and also takes other factors like sperm survival, temperature fluctuations, past cycles and cycle irregularities into account – to determine whether you are fertile or not and calculate your red and green days. Optional ovulation (LH) tests also help the app to pin-point your ovulation and determine these days.

Natural Cycles goes beyond just contraception. Our “Plan a Pregnancy” mode can support you in your journey to become pregnant by letting you know the days that you are fertile. Find out about the “Plan a Pregnancy” mode here.

The number of green days increases as the algorithm gets to know each woman’s individual cycle pattern. If you have a regular cycle, a steady temperature (without many deviating entries) and enter measurement data regularly (at least 5 days a week), then you can expect to get around 60% green days after three months of using Natural Cycles.
You and your partner should be comfortable with using protection like a condom or abstaining from sex on these days to prevent a pregnancy.

Natural Cycles does not protect against Sexually Transmitted Infections (STIs). Please do keep in mind that the only method of contraception that protects against STIs is the male and female condom. Should you have reason for concern, be sure to use them at all times.

Natural Cycles is an effective*, natural method of contraception and is the first CE marked app intended to be used as a contraceptive and cleared by the US FDA. It is powered by a smart algorithm that can determine a woman’s daily fertility using basal body temperature. Unlike other fertility awareness methods, Natural Cycles uses only objective data and minimises human error as the app does all of the calculations and interpretations for the user.

*Natural Cycles is 93% effective with typical use. This means that in a year of use, an average of 7 women out of 100 will get pregnant while using Natural Cycles.

Our CE marking and FDA clearance have been granted based on mandatory clinical data that demonstrates that the effectiveness rate of Natural Cycles is 93% with typical use. This means that Natural Cycles is the first app that has been assessed and deemed effective enough in preventing pregnancy to be categorised as a method of contraception in Europe and the US.

We offer a free trial period of 30 days so you can see if the app is right for you before committing to a subscription.

There are two subscription options: either an annual and monthly subscription. See here for pricing.

Our ovulation prediction algorithm plays an important part in detecting your fertile days. In the graph view you can see your predicted ovulation window – this also shows when the algorithm is waiting to confirm your ovulation and once it has been confirmed. Your predicted ovulation is visible in the Today and Calendar views as well. If the algorithm doesn’t detect your ovulation, you may have had an anovulatory cycle. This means you did not ovulate this cycle. We will let you know if this happens by sending you a message in the app.

Natural Cycles works by analyzing your basal body temperature measurements. That’s why it is important to measure with a two decimal basal thermometer, after you have slept enough (at least 4 hours) and before getting up and out of bed. You place it under your tongue, as far back as possible and press the button to turn it on. Once it beeps, enter your measured data into the app. A handy tip is to place your thermometer on top of your phone so you remember to measure first thing in the morning.

We recommend that you measure your temperature at least five out of seven days in the week. The app will still work effectively if you forget to measure, but will give you more red days.