Clue Birth Control
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Please read this user manual before you start using Clue Birth Control.
Table of contents
Jump to section
Understanding pregnancy risk
Understanding banner messages
Entering your period start date
Viewing your cycle data
Keeping your Clue app updated
Protecting your private data
Add a secure app passcode
Customer support and troubleshooting
If it’s been 40+ days since your last period
If your period is late
If you become pregnant while using Clue Birth Control
More about cycle length
Please read this User Manual before you start using Clue Birth Control.
Intended use Clue Birth Control is a software application for contraception for women ages 18-45 years old, to monitor their fertility and prevent pregnancy. Clue Birth Control is suitable for women with predictable 20-40 day cycles, who have not recently used hormonal birth control.
Type of use Over-The-Counter (OTC) use.
Contraindications for use There are no known contraindications for use of Clue Birth Control.
No contraceptive method is 100% effective. There is still a chance that you could become pregnant, even if you use Clue Birth Control.
Even when using Clue Birth Control exactly as directed, you could still have an unintended pregnancy. Clue Birth Control is 92% effective with typical use, which means that about 8 in 100 women are expected to become pregnant during one year of use. If used exactly as directed (perfect use), Clue Birth Control is 97% effective. This means that even among those who never have unprotected sex on a high risk day, about 3 in 100 are expected to become pregnant during one year of use. To understand what perfect and typical use is, please see the section “Perfect vs. typical use”.
If you have sex on high risk days, you must use an additional barrier method for protection, preferably condoms.
Track your period start dates in the app as accurately as possible. The accuracy of predicting high risk and low risk days depends on the accuracy of the information you track.
Using Clue Birth Control will not protect you against any sexually transmitted infections or diseases (also called “STIs” or “STDs”). Only abstinence or condoms protect against STIs/STDs.
You may have to stop using Clue Birth Control if your cycle length becomes too long, too short, or too variable after starting to use it. So you should have alternate contraception planned. The app will notify you if this is the case, letting you know that accurate risk predictions are no longer possible.
If you have one or more cycles of 36-40 days in your last 12 cycles, you may have a higher risk of pregnancy.
Do not use the Clue app as a birth control method if you don't have the Clue Birth Control mode activated.
Do not use if the possibility of getting pregnant is unacceptable for you, or if pregnancy would put you or the fetus at risk.
You are 18 to 45 years of age.
The cycles of younger or older people outside of this age range can vary more, which makes predictions less reliable and therefore less safe.
You have predictable 20-40 day cycles that varied by 9 days or less over your last 12 cycles.
Cycle length is the number of days from the first day of a period to, and including, the day before the next period. To make sure you understand cycle length, please see the illustration "What's the difference between a 'cycle' and a 'period'?"
To determine the variation of your cycle, subtract the length of your shortest cycle from the length of your longest cycle of your last 12 cycles. For example, if the shortest cycle length was 25 days and the longest was 35 days, then the difference is 10 days.
What's the difference between a 'cycle' and a 'period'?
You have had 3 eligible cycles (4 periods) since stopping hormonal birth control or removing a copper IUD.
Hormonal birth control or a non-hormonal IUD: You can use Clue Birth Control if you have had at least 3 cycles (4 periods) since stopping any form of hormonal birth control, such as the pill, minipill, ring, patch, implant, or copper IUD, and if the most recent 3 cycles were 20-40 days long, and the difference in length between the longest and shortest cycle was 9 days or less.
Birth control shot: You can use Clue Birth Control if you have had at least 3 cycles (4 periods) since the end of the protection period of your most recent shot (the most common contraceptive injections last for 3 months), and if the most recent 3 cycles were 20-40 days long, and the difference in length between the longest and shortest cycle was 9 days or less. Speak to your healthcare provider to determine when and what kind of contraceptive injection you were given.
You have had 3 eligible cycles (4 periods) since pregnancy.
You can use Clue Birth Control if you were recently pregnant only if you have had at least 3 cycles (4 periods) since the end of the pregnancy and if these most recent 3 cycles were 20-40 days long, and the difference in length between the longest and shortest cycle was 9 days or less. You can use Clue Birth Control while breastfeeding as long as your most recent 3 cycles were 20-40 days long, and the difference in length between the longest and shortest cycle was 9 days or less.
Please note: When getting started with Clue Birth Control, you will be asked a series of questions in the Eligibility Checklist to determine whether or not you meet the requirements for using Clue Birth Control.
If you’re not eligible to use Clue Birth Control based on the answers you provide in the Eligibility Checklist, you will not be able to use Clue Birth Control. The Eligibility Checklist is a series of questions to find out if you can use Clue Birth Control. If your answers to the questions change, you can try completing the Eligibility Checklist at a later time, but only after 30 days, at the earliest. Meanwhile, you may talk to your healthcare provider about alternative birth control options.
Always check Clue Birth Control for your risk predictions before you have sex.
On high risk days, always use a barrier method such as a condom every time you have sex that may result in pregnancy. To learn more about other barrier methods, see Appendix.
If you do not have Clue Birth Control with you or are not sure if it is a high risk or low risk day, use a barrier method for protection, such as a condom, or do not have sex that may result in pregnancy.
Always consult your healthcare provider for decisions around your reproductive health and contraception.
You can discuss with them whether Clue Birth Control is the right option for you.
Clue Birth Control is 92% effective with typical use, and 97% effective with perfect use. To understand what perfect and typical use are, see the section “Perfect vs. typical use”.
Only download the Clue app from the Apple App Store. Alternative app stores may not have the correct version of the Clue app.
Keep the Clue app updated so that you have the latest version and protect your data by using secure WiFi networks. For added security, set up a passcode in your app settings, as described in the section “Protecting your private data”.
If you are taking any hormonal medications that may influence your cycle length such as hormones, treatments for acne or high blood pressure, or steroids for asthma (this is not a complete list), Clue Birth Control might not be right for you. Consult your healthcare provider about any medications or supplements you are currently taking before starting a new contraceptive method.
If you are taking a medication that could impact fetal development, or have a medical condition that could be worsened by pregnancy, talk to your healthcare provider before using Clue Birth Control.
If you have sex on a high risk day without a barrier method, consult your health care provider about your emergency contraceptive options.
If you have used emergency contraception in your current cycle, you will need to wait until your next period begins before using Clue Birth Control. To prevent pregnancy until then, use a barrier method such as a condom when having sex that may result in pregnancy. If your period does not begin, consult your healthcare provider.
Clue Birth Control is a mode of the Clue app, and it relies on the Clue app in order to operate correctly.
In order to use Clue Birth Control, you must first download the Clue app and sign up for an account with a valid email address. Here’s how to set up your Clue account:
Connect to the Internet.
Download and install the Clue app from the Apple App Store.
Open the Clue app and follow the instructions to sign up for an account. Make sure to verify your email address.
Clue Birth Control mode is accessible through the More Menu
Open the Clue app and go to the More Menu and tap on “Mode”. Then select the mode “Clue Birth Control”.
Once selected, you’ll receive an overview of Clue Birth Control, how safe it is, and whether or not it could be a good fit for you.
You will be taken step-by-step through the Eligibility Checklist for using Clue Birth Control. The Eligibility Checklist is a series of questions to find out if you can use Clue Birth Control.
To start using Clue Birth Control, you’ll have to confirm your age.
You will be asked a number of questions about your cycle length, birth control methods and pregnancies over the last 12 months.
If you successfully complete the Eligibility Checklist, you’ll be asked to accept the Clue Birth Control terms and conditions. If you don’t successfully complete the Eligibility Checklist, you can try again in 30 days.
Then you will need to pay and subscribe to Clue Plus in order to use Clue Birth Control.
You must track at least one period to receive predictions using Clue Birth Control. To do this, track your most recent period start date. If you do not know the start date of your last period, wait until you get your next period, then enter your period start date. Or, if you have previously tracked a period in the Clue app, confirm the date of your most recently tracked period start date.
If you have had unprotected sex since your last period start date, you should wait until your next period start date to begin using Clue Birth Control. This is to make sure that you are not pregnant when you start using it.
You can now begin using Clue Birth Control. When you start using Clue Birth Control, it will take a few cycles for the app to learn your personal cycle pattern. You will initially see the maximum number of high risk days (16 days). Over time, the number of high risk days can decrease as you enter more period start dates.
To understand how Clue Birth Control determines high and low risk days, read more here.
To unsubscribe from Clue Birth Control:
You can unsubscribe from Clue Birth Control through your device’s subscriptions. This will take effect as soon as your subscription period is over. You can continue using Clue Period Tracking mode to track your cycles. When your subscription period ends, the Clue Birth Control mode will be switched off and you will go back to the regular Clue app automatically.
On your iOS phone or tablet, go to Settings. Then tap your name. Select Subscriptions. Then select the subscription you want to manage. Scroll down and select Cancel Subscription.
Clue Birth Control calculates and displays your daily pregnancy risk as high or low, for each day of your cycle, based on the period start dates you have entered. You need to be connected to the Internet to use Clue Birth Control in the Clue app. When connected to the Internet, you can view the predicted risk of pregnancy for all the days of your cycle on the main Cycle View or in the Calendar View. It’s important to track your periods consistently to get accurate predictions. You can always return to the Cycle View by tapping the cycle icon in the bottom navigation bar. To get to the Calendar View, tap the calendar icon in the navigation bar.
This is what your Cycle View in Clue Birth Control could look like on a high risk day.
High risk days: On the days when the risk of pregnancy is high, you will see this text on an orange banner at the top of the screen: “Your risk of pregnancy today is high. Use protection".
On high risk days, you must use a barrier method such as a condom to prevent pregnancy. See Appendix for a list of all barrier methods and for important information on the risk of pregnancy with each.
Low risk days: On days when the risk of pregnancy is low, you will see this text on a green banner at the top of the screen: “Your risk of pregnancy today is low.” For more information on high and low risk days, tap on “Learn More” on the banner message.
Clue Birth Control will always let you know if it is unable to provide reliable predictions. In some cases, you may need to take action for predictions to resume. In other cases, Clue Birth Control may have detected that it can’t provide predictions because your cycle no longer meets the eligibility requirements for safe and effective use. If you see a warning, follow the instructions to solve it if possible and use a barrier method such as a condom to prevent pregnancy until the warning disappears.
Your cycles no longer fit requirements: Clue Birth Control monitors your cycle lengths and will alert you if your cycles fall outside of the range (too short, too long, or too variable) for using Clue Birth Control. If this happens, the following message will appear in an orange banner at the top of the screen: “Your entered cycles no longer fit the Clue Birth Control requirements. Use protection.” This means that Clue Birth Control can’t accurately predict which days are high risk for pregnancy. Inaccurate predictions could put you at a higher risk of pregnancy. You will no longer be able to use Clue Birth Control until you experience 12 subsequent, eligible cycles.
Your cycles no longer fit requirements
You haven’t tracked your period: Clue Birth Control can detect that you may be overdue for entering your last period start date. If this happens, the following message will appear at the top of the screen: “You have not tracked your period for a while. For now, use protection.” Enter the correct period start date before proceeding to use Clue Birth Control.
You haven't tracked your period
You need to enter your period start date: Clue Birth Control relies on your period start dates to provide predictions. If you have not tracked any period start dates, the following message will appear at the top of the screen: “You’ll get risk predictions after you’ve entered your first period. For now, use protection.” Track your last period start date and follow the instructions in the app to begin getting predictions from Clue Birth Control.
You need to enter your period start date
You’re offline: You need to be connected to the Internet to use Clue Birth Control. If you enter your period start date while you are offline, the app cannot predict your risk for pregnancy until you are online, so you will see the following message: “You’re offline. Go online to see your risk prediction. For now, use protection.” Clue Birth Control is unable to predict your pregnancy risk while offline. Use a barrier method such as a condom when having sex that may result in pregnancy.
Your period data didn’t sync: When you see the message “Looks like your period tracking didn’t sync due to a technical error. For now, use protection”, it means the data you have just entered has not been processed by Clue Birth Control yet. This means it can’t make a prediction for you. If you see this message, Clue Birth Control is trying to solve the problem. Close and restart the app or try again later. Use protection until the app is synced correctly and offers you a prediction.
Your period data didn't sync
Technical error: When unexpected technical problems happen, the following message will appear at the top of the screen: “There’s an unexpected technical error. To be sure you’re safe, use protection.” Clue Birth Control is unable to predict your pregnancy risk in this case. Use a barrier method such as a condom when having sex that may result in pregnancy.
There's an unexpected technical error
Loading screen: The app may take several seconds to process your data to make a prediction for you. If you see the loading screen reading “Updating your predictions,” be patient and your prediction should appear. If the app appears stuck on the loading screen, close and restart the app.
Clue Birth Control relies on your entered period start dates to predict your risk of pregnancy each day. For this reason, it’s important to accurately track your period in Clue Birth Control every time your period begins.
To enter data in Clue Birth Control, tap Track (“+” sign) in the bottom navigation bar to begin tracking. Select the desired date in the date selector at the top of the screen.
To track your period start date, make sure the correct date is selected in the date selector at the top of the screen, and navigate to the Bleeding tracking category. Select “Light”, “Medium”, or “Heavy” to indicate the level of bleeding. Any of these options will count as your period start date. Tap Done to save the period start date.
Spotting should not be confused with light bleeding. Track “Spotting” only if the blood is sporadic and not a continuous flow. Spotting does not soak your underwear with blood. This should not be counted as the first day of your period.
You can edit period dates by tapping Track (“+” sign) in the bottom navigation bar. At the top of the app screen, select the date you wish to enter as your period start date. Tap “Light”, “Medium”, or “Heavy” to track your period blood volume. When you tap Done, your period dates will be automatically updated.
You can view your high risk days in the Calendar View and Cycle View.
The Calendar View will show the following:
High risk days in orange for your current cycle
Banner messages that will let you know if Clue Birth Control is unable to provide reliable predictions at that time
Link to “Learn More” in the banner notifications
Predictions for the next three periods and PMS days
If you have been tracking your period start dates for more than one cycle, you will see previous period dates
This is what your Calendar View in Clue Birth Control could look like on a high risk day
The Cycle View will show the following:
High risk days in orange for your current cycle
Banner messages that will let you know if Clue Birth Control is unable to provide reliable predictions at that time
Link to “Learn More” in the banner notifications
Your current cycle’s period start date
Tap on a date in your calendar or cycle and swipe up to view your tracking history on a specific day. You can also enter past period start dates or other cycle experiences by scrolling back in your calendar and tapping Track (“+” sign).
Clue Birth Control is a mode of the Clue app, and it relies on the Clue app in order to operate correctly. Always make sure to keep the Clue app updated to the latest version. We recommend that you set your smartphone to automatically update the Clue app.
If an update is required to ensure that Clue Birth Control works correctly, you will not be able to use it until you have updated the app.
Here's how: On your iOS device: To set your smartphone to automatically update your app, go to Settings. Then tap your name. Select iTunes & App Store. Then turn on App Updates. The app will automatically update when updates are available.
Clue Birth Control was developed to minimize cybersecurity risks. However, as with all apps that process your private data, there are some things you can do to further protect your data from being seen by others.
Use secure WiFi networks
If you connect to unsecured (public) WiFi networks, your Internet-based communications are more vulnerable, including all data that is processed by your apps. A secure (private) WiFi network is one that you need a password to access.
Add a secure app password
If you want to keep the Clue app and Clue Birth Control more private than the rest of your phone, you can protect it with an additional passcode. If you don’t protect your Clue app with an additional passcode, then anyone who can unlock your phone can also look at your Clue app, including your Clue Birth Control data, the information you’ve tracked, and your personalized predictions.
You can further protect your data in the Clue app with an additional passcode.
Here's how: On your iOS device: To set up a passcode for the Clue app on iOS, tap the More Menu and then select Settings. Then tap Passcode and select Enable Passcode. Follow the instructions to set a new 4-digit passcode.
If you experience a problem using Clue Birth Control, you can contact Clue’s Support Team through your Clue app. Tap the Menu icon. Then tap Support and choose “Clue Birth Control”.
You can also contact the Clue Support Team through the website at https://support.helloclue.com/hc/en-us.
Clue Birth Control can only be used if your last 12 cycles were between no more than 40 days. When it has been more than 40 days since your last tracked period, Clue Birth Control will not provide pregnancy risk predictions.
If you had a period and forgot to track it, enter the period using the instructions under the section “Entering your period start date”, for predictions to resume.
If it’s been more than 40 days since your last period, you’ll receive a survey via email asking why you stopped using Clue Birth Control and whether or not you’ve experienced a pregnancy.
Please respond to our follow-up survey; we are legally obliged to do our best to understand what happened so that we can continuously monitor and improve Clue Birth Control.
Take a pregnancy test (a urine test will provide the quickest results) and call your healthcare provider if your period has not started more than 9 days after the predicted start date. It’s recommended to wait to take a pregnancy test at least until you expect to get your period.
If that test is negative and you don’t get your period after another week, you should take another pregnancy test. This could be because the first test was taken too early to detect the pregnancy. If you find out you are pregnant or if the test is negative and you still do not get your period, consult with your healthcare provider.
When Clue Birth Control is used correctly according to instructions for use, it can greatly reduce, but does not eliminate, the risk of pregnancy.
If you experience an unintended pregnancy while using Clue Birth Control, you should speak to your healthcare provider who may recommend options for pregnancy management or termination.
Please inform Clue’s Support Team directly by going to the More Menu in the top corner, then tapping Support and choosing Clue Birth Control. Alternatively you can go to: https://support.helloclue.com/hc/en-us.
After contacting the Support Team, you’ll receive a survey via email. Please respond to our follow-up survey; we are legally obliged to do our best to understand what happened so that we can continuously monitor and improve Clue Birth Control.
When your pregnancy is over and your period resumes, you can start tracking your period again. After pregnancy, you will need to experience 3 eligible cycles (4 periods) before using Clue Birth Control again. Please see “Eligibility Criteria” for more information.
Though cycle length can change and can become more variable as women approach menopause, a reliable contraceptive method is still important during this time for women who wish to avoid pregnancy. You can use Clue Birth Control as a contraceptive method up to 45 years of age as long as your cycles remain in the cycle length range of 20 to 40 days, with 9 days or less difference between your shortest and longest cycles. If your cycles fall outside this range, then Clue Birth Control should not be used for pregnancy prevention. Note that the efficacy study for Clue Birth Control did not include people older than 39 and may not apply to this age group. Contraceptive studies typically include only people who are younger than 40 years old (the ages of highest fertility), to avoid an inflated efficacy rate.
If you have a diagnosed medical condition that causes irregular cycles, such as polycystic ovary syndrome (PCOS) or thyroid-related conditions, you can use Clue Birth Control as long as your cycles fall within the eligibility criteria. If your cycles do not meet the eligibility criteria, then Clue Birth Control cannot be used for pregnancy prevention. Please talk to your healthcare provider about your medical diagnoses.
Clue Birth Control has a perfect use failure rate of 3%, which means that 3 out of 100 women who use the app perfectly for one year are expected to get pregnant either because:
They had unprotected sex on a day that was actually a high risk day but was incorrectly calculated by the app as a low risk day (i.e. method failure); or
They had protected sex on a high risk day with a barrier method but were still exposed to ejaculate, perhaps due to method failure such as a condom breaking, leaking, or coming off. (For instructions on how to properly put on and use a condom, read more here)
Clue Birth Control has a typical use failure rate of 8%, which means that 8 out of 100 women who do not follow instructions perfectly are expected to get pregnant during one year of use.
Some examples of typical use failures are:
Sex without a barrier method, such as a condom, on a high risk day;
Any cause of failure included under perfect use, as mentioned above.
Note on condoms and other barrier methods:
The risks of pregnancy referred to above are based on the use of an external male condom, or abstinence from sex, during high risk days. External male condoms are the barrier method with the lowest risk of pregnancy. Efficacy rates may differ with the use of other barrier methods. For a list of all barrier methods and their stand-alone efficacy rates, see Appendix.
See the published research article for additional information about Clue Birth Control efficacy.
A clinical trial was conducted to test the effectiveness of the algorithm Clue Birth Control uses to predict high risk and low risk days. This trial followed 718 women for up to 13 cycles from February 2017 to October 2018. Participants provided data on 6,616 cycles, which included detailed information on sexual activity and behavior throughout the study. The study found that during typical use, when the method was not always used perfectly, the algorithm was 94.2% effective over one year of use (i.e. the method is estimated to have a 5.8% typical use failure rate). When used perfectly, the algorithm was 99.0% effective in preventing pregnancy over one year of use (i.e. the method is estimated to have a 1.0% perfect use failure rate).
A clinical trial’s results represent an estimate of the population efficacy rate. Because Clue is committed to ensuring that our product is at least as effective as the efficacy claim we present to our users, if not more so, we report the upper bound of the 95% confidence interval around these statistics, as calculated during the efficacy trial:
Typical use: 5.8% (95% CI: 3.6% - 8.1%)
Perfect use: 1.0% (95% CI: -0.9% - 2.9%)
Therefore, the marketed efficacy rates are 92% effective with typical use and 97% effective with perfect use.
Other contraceptive methods
This table provides information about the effectiveness of different contraceptive methods. It includes the percentage of women experiencing an unintended pregnancy during the first year of typical use and the first year of perfect use of a contraceptive method.
Percentage of women experiencing an unintended pregnancy within the first year of use
Hatcher RA. Contraceptive technology. 2018
Name of Manufacturer:
Clue by Biowink GmBH
Address of Manufacturer:
Adalbertstrasse 7-8, 10999 Berlin, Germany
Clue Birth Control
Date of publication:
Document version: EN V1
This version of the User Manual applies to iOS versions 44 onwards of the Clue App.
Clue by Biowink GmbH,
Adalbertstrasse 7-8, 4/5th floor,
10999 Berlin Germany
2021-10 Made in Germany
Consult electronic instructions for Use