Frequently asked questions
Read up on the answers to the questions we get asked the most
Unlike free apps, our monthly subscription helps protect you and your data. We will never sell your data – though you will have the option to help us further research women’s health. Check our science page for more info.
Birth control costs money both to make and supply. Our subscription fee means we can continue offering another hormone-free birth control option. If you live in the US, you can now get your Natural Cycles subscription reimbursed through your insurance provider.
We offer two subscription options: either an annual or a monthly subscription. Click here for pricing. We also offer a free demo mode once you have downloaded the app so you can get a feel for using Natural Cycles before committing to a subscription. Download the app for iOS here and download for Android here.
Yes! For our US users, Natural Cycles subscriptions are eligible for reimbursement through your FSA/HSA program. Simply sign up for Natural Cycles as you normally would, and request an itemized receipt at checkout. This PDF receipt should have all the information needed for reimbursement. Simply download the PDF and share it with your employer.
We have also partnered with FSAstores.com. Visit their website to purchase Natural Cycles products using your FSA/HSA credit card.
Don't have an FSA or HSA? If you live in the US you can now get your Natural Cycles subscription reimbursed through your insurance provider.
Natural Cycles is intended for women 18 years and older, and can be used to prevent a pregnancy (contraception) or plan a pregnancy (conception). With over 3 million registered users, there are many reasons to use Natural Cycles. Some users (or Cyclers, as we refer to them) choose Natural Cycles because they suffer from negative side effects from hormonal birth control, others want to have a better understanding of their body, and some come to Natural Cycles because while they are not ready to have a child now, they want an option that can help them plan a pregnancy when they are ready.
You can’t get pregnant every day of your cycle. The fertile window is six days in the cycle. It begins five days before ovulation, as sperm can survive up to five days in the body under the right conditions, and ends on ovulation day. When the egg is released on ovulation day, it can only survive for a maximum of 24 hours. Only during these six days is it possible to get pregnant through unprotected sexual intercourse.
Everyone has a unique menstrual cycle pattern. For example, the cycle length and the day ovulation occurs vary from person to person and cycle to cycle. Since your ovulation day can change from cycle to cycle, determining when you may ovulate and confirming whether you have ovulated is crucial for knowing your daily fertility status.
Body temperature changes during the menstrual cycle and can be used to detect ovulation and identify your fertile window. Natural Cycles is an app powered by a regulated and certified algorithm based on body temperature that learns the pattern of your unique cycle to work out each daily fertility status.
Natural Cycles is the first and only app of its kind to be FDA Cleared and CE Marked. Most other fertility apps assume your cycle is 28 days long. This means the fertile window they give you is not personalized to you. Our algorithm significantly reduces the risk of you being assigned an incorrect fertile day as it uses your personal data. This reduces the risk of unwanted pregnancy or can help you plan pregnancy with greater precision.
While some fertility apps make money from selling data for advertising, we never have, and never will sell our users’ data. Find out why women around the world choose Natural Cycles.
During your menstrual cycle, your temperature rises after ovulation and then falls slightly when your next period comes. This is due to a change in your body’s hormone levels. The Natural Cycles app uses the science of your cycle to work out your fertile days based on body temperature. That’s why you need to use a device that collects temperature data, such as a basal thermometer, an Oura Ring, or Apple Watch.
Charting body temperature is not a new birth control or fertility method. However, Natural Cycles pairs this traditional method with an algorithm that learns the pattern of your unique cycle to predict your fertile window. Natural Cycles can accurately capture every unique cycle by taking cycle irregularity, temperature fluctuations, any recent usage of hormonal contraception, ovulation day variation, sperm survival, and several other essential factors into consideration.
Natural Cycles uses body temperature data, period data, and optional luteinizing hormone (LH) data to calculate your daily fertility status — red when you’re fertile and need to use additional protection to prevent pregnancy, and green when you’re not fertile, and no additional protection is needed. Read more info on how the app works.
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 during your first 1-3 cycles. This ensures that the app is effective from the first day of use. Once Natural Cycles has detected your ovulation, you are likely to receive more Green Days. You can rely on the fertility status indicated by the app from the first day of use.
The number of fertile/non-fertile days you get will vary. As every body is different, there is no set number of Red Days you will receive. Although we're only actually fertile for six days in any menstrual cycle, the number of Red Days you get depends on the regularity of your cycle, how often you input data into the app, and the stability of your basal body temperature. The algorithm will also give an extra Red Day or two as a buffer for extra protection in case your ovulation day moves.
Give the algorithm time to learn your cycle and try to measure at least five days a week to increase the number of Green Days. Find out more about how Natural Cycles works.
Analyzing your unique temperature data is key to how Natural Cycles works, but as we know everyone’s routine is different. Temperature data can be collected using the NC° Thermometer (this is different to a regular fever thermometer), or by pairing a measuring device like an Oura Ring or a compatible Apple Watch with the Natural Cycles app.
With the NC° Thermometer, measure your temperature (first thing) when waking up (before sitting up, drinking water, snoozing, or getting out of bed). We recommend keeping the thermometer close to your bed. After measuring, open the Natural Cycles app to sync your data and see your daily fertility status.
With an Oura Ring, your temperature trend data is measured overnight. Wear your Oura Ring to sleep. When you wake up, open the Oura App and NC° app to sync your data and see your daily fertility status. If you are using a Gen3 Oura Ring or later, you will also need an Oura subscription to use the integration.
With Apple Watch, your temperatures are measured and sync with the Natural Cycles app while you sleep. Wear your Apple Watch Series 8+ to bed at night. Open the NC° app to see your daily fertility status when you wake up.
It’s not a problem. We all forget things, and we all have days when we don’t get enough sleep, oversleep, or feel under the weather. We recommend that you aim to measure your temperature at least five days a week. Frequently forgetting to measure will not change the effectiveness of the app, but you may get more Red Days as a result.
Certain circumstances may affect your basal temperature. This can lead to variating temperatures and make it harder for the algorithm to track your cycle. To help our algorithm learn about your cycle and find your ovulation, use the “Exclude temperature” function in the app if you feel hungover or sick. If you measure with the NC° Thermometer, you should also exclude a temperature if you slept differently (2 hours more/less than usual). An excluded temperature is not taken into account by the algorithm when calculating your fertility status.
Medication can also affect your temperature. If you take regular medication or antipyretics (fever-reducing substances), it’s worth consulting with your doctor to discover its impact on your basal body temperature.
Check out our User Manual for more info on what can affect temperature.
Yes. The effectiveness of Natural Cycles is supported by clinical evidence, which shows Natural Cycles is 93% effective under typical use. Under perfect use, i.e. if you never have unprotected intercourse on Red Days, Natural Cycles is 98% effective. Read more on the science behind our effectiveness.
Forgetting to measure doesn’t impact how effective NC° Birth Control is at preventing pregnancy. However, if the app doesn’t have enough data due to poor sleep or forgetting to measure, you might get more Red Days (when you’ll need to abstain from sex or use protection).
You don’t have to wait for Natural Cycles to learn your cycle before you can start using it because – Natural Cycles is effective from the first day of use!
Natural Cycles is just as effective if you have irregular menstrual cycles (i.e. cycles lasting fewer than 21 days or greater than 35 days in length).
If your cycle is very irregular, Natural Cycles may be less suitable for you, as you may be given more Red Days (these are a safety buffer since ovulation days can change with irregular cycles).
However, those with irregular cycles often find that Natural Cycles is a useful tool for tracking their irregularities and better understanding their bodies. Find out if Natural Cycles could work for you.
It depends. If you are using non-hormonal birth control (condoms, copper IUD, etc.), you can get started right away.
Hormonal birth control affects your cycle and temperature, so you need to stop using it before you can start Natural Cycles. However, you can try the app in demo mode before coming off hormonal birth control.
After stopping hormonal birth control, cycle irregularities are common. Speak to your healthcare professional if you have any concerns.
Yes. You can get started with Natural Cycles at any point after pregnancy, but you will only be given Red Days until your first ovulation is confirmed. The timing of your first ovulation post-birth can vary widely from person to person. You can read more on using Natural Cycles while breastfeeding here.
Absolutely. Natural Cycles goes beyond birth control. Learning about your cycle also gives you the power of knowing when it’s the best time to conceive. NC° Plan Pregnancy tells you the days when you are most fertile, and it can also let you know when it’s the optimal time to take ovulation or pregnancy tests. Once you log a positive test in the app, you can start using NC° Follow Pregnancy – here, you’ll get regular updates on the progress of your pregnancy.
To use NC° Plan Pregnancy, you need to measure your body temperature, input your temperature and period data, and then the Natural Cycles algorithm will provide your daily fertility status. In NC° Plan Pregnancy, the fertile window is presented in a scale of red colors, where the most fertile day has the darkest shade of red, and the lightest red color indicates that fertility is less likely. Non-fertile days have a light green color.
Natural Cycles gives you the information you need to time intercourse and maximize your chances of conceiving. Our research shows that, on average, it takes three cycles or less to become pregnant using NC° Plan Pregnancy.
Natural Cycles is a regulated medical device that follows GDPR and is committed to safeguarding your data with the highest level of security and encryption. Protecting user information has always been a top priority for Natural Cycles. Now more than ever, sensitive data requires greater protection and regulation, which is why you can rest assured we will continue to ensure your data is always kept secure. Visit our data security page to learn more.
We are FDA Cleared in the US and CE Marked in Europe as a medical device for contraceptive use. We are also listed in the ARTG in Australia and on the SMDR in Singapore. Our certifications have been granted based on mandatory clinical data that demonstrates that the effectiveness rate of Natural Cycles is 93% with typical use and 98% with perfect use (when using protection on each Red Day). Natural Cycles is the first app to be assessed and recognized as a method of birth control in Europe and the US. Read more about our regulatory clearances.
The Food and Drug Administration (FDA) is a federal agency of the Department of Health and Human Services in the United States that regulates the sale of everything from drugs to electronic products to ensure consumer safety. Since Natural Cycles is a medical device, we were required to undergo a strict regulatory clearance process to demonstrate the safety and effectiveness of our product before we could sell it.
In 2018, the FDA cleared Natural Cycles as the first contraceptive app, making birth control history. It remains the only FDA Cleared birth control app on the market today.
To get started:
- Sign up for Natural Cycles
(purchase a subscription and measuring device)
- Download the app
- Follow the steps to set up your device
- Start measuring!
Still got questions?
Check out our support portal Cyclerpedia, where you’ll find articles on everything you need to know about Natural Cycles.