Illustrations by Marta Pucci

Non-Hormonal Birth Control

How effective is Clue Birth Control?

Comparing Clue Birth Control to other types of birth control

Clue Birth Control is a digital fertility awareness-based method (FABM) of contraception that is hormone free. Clue Birth Control is 92% effective at preventing pregnancy when used typically and 97% effective at preventing pregnancy when used perfectly (1). It has no side effects, and doesn’t require a visit with a healthcare provider to access it (although it’s always good to talk with your healthcare provider about which contraception is right for you). 

Clue Birth Control works by identifying the days of each cycle with a high and low risk of pregnancy. You only have to track your period start date for Clue Birth Control to calculate your daily risk of pregnancy. You can check the app each day to instantly know if your risk of pregnancy is high or low. For Clue Birth Control to be effective, on high risk days you must use a barrier method such as a condom every time you have sex that may result in pregnancy.

an image of 3 mobile screens of the Clue app

Prevent pregnancy by tracking your cycle with Clue Birth Control

  • Download the Clue app on the App Store
  • Download the Clue app on the Play Store

4.8

An illustration of a five star rating

2M+ ratings

If you’re considering using Clue Birth Control for contraception, here’s what you need to know about how effective it is at preventing pregnancy and how it compares to other birth control methods. 

How effective is Clue Birth Control?

Clue Birth Control is 92% effective with typical use* (1). Typical use describes how well a method works for people who are using the method “typically” (2), which includes occasionally using the method incorrectly or not using the method every time they have sex that may result in pregnancy. Clue Birth Control is 97% effective with perfect use* (1). Perfect use describes how well a birth control method prevents pregnancy when used consistently and correctly every time. 

When talking about different kinds of birth control, perfect use and typical use efficacy rates are often compared to the likelihood of avoiding pregnancy over a year of not using any method of birth control, which is about 15% (2). This means that over a year, 85 out of 100 people will become pregnant when using no birth control method (2). As a comparison, 8 out of 100 people are expected to become pregnant when using Clue Birth Control typically over one year, and 3 out of 100 people are expected to become pregnant when using Clue Birth Control perfectly over one year (1). 

So, how do you use Clue Birth Control “perfectly”? To ensure the effectiveness of Clue Birth Control, you need to use a barrier method such as a condom every time you have sex that may result in pregnancy on a high risk day. You can find out if Clue Birth Control is right for you and read exactly how to use it here

How do I know Clue Birth Control is effective?

Researchers at the Institute for Reproductive Health (IRH) at Georgetown University conducted a study on Clue Birth Control. This study tested the effectiveness of the algorithm (a sophisticated mathematical prediction) Clue Birth Control uses to predict high and low risk days. The study included 718 women (who participated after their permission was obtained) for up to 13 cycles from February 2017 to October 2018. Researchers collected data on 6,616 cycles, including detailed information on sexual activity and behavior throughout the study (1).

The study found that when used perfectly, the Clue Birth Control algorithm was 97% effective at preventing pregnancy (1). When the method was not always used perfectly, or used typically, Clue Birth Control was 92% effective* (1). The calculation for typical use included people who became pregnant while using Clue Birth Control, as well as people who dropped out of the study and could possibly have become pregnant, but did not confirm a pregnancy (1).

What’s the difference between typical and perfect use?

The researchers who conducted the study on the algorithm behind Clue Birth Control determined that it is effective for pregnancy prevention (1). If you’re considering Clue Birth Control, you probably want to know how to make it as effective as possible for you.

Clue Birth Control has a perfect use failure rate of 3%, which means that 3 out of 100 people who use the app for one year are expected to get pregnant because:

  • They had unprotected sex on a day that was actually a high risk day when the app incorrectly told the user it was a low risk day. 

  • They had protected sex on a high risk day with a condom, but the condom failed because it broke, leaked, or came off. 

Of the 718 study participants, one person in the study became pregnant while using the app correctly. Researchers couldn’t determine if it was because the app incorrectly identified the high and low risk days for that cycle or if a condom failed during sex (1). 

Clue Birth Control has a typical-use failure rate of 8%, which means that 8 women out of 100 are expected to get pregnant during one year of use when not always using the app correctly and consistently (1). In the study, the main reason the app failed as birth control with typical use was because a person had unprotected sex without a condom on high risk days (1). 

How does Clue Birth Control compare to hormonal birth control?

Hormonal birth control is considered to be very effective (2). It is a great pregnancy prevention tool for some people, while others prefer hormone-free contraception to avoid side effects or for other medical, personal, or religious reasons. 

Hormonal methods of birth control contain either progestin or a combination of both progestin and estrogen (typically ethinyl estradiol) (2). Hormonal birth control options include the implant, the intrauterine device (IUD), the shot, the pill, the ring and the patch. These methods of birth control have high rates of efficacy, but if you choose a method that is difficult for you to use correctly, it could lead to unintended pregnancy (2).

All hormonal birth control works to prevent pregnancy by preventing ovulation or thickening cervical mucus, and many do both (2). Depending on the method of hormonal birth control, there may be additional factors that help to protect against pregnancy (2). 

Clue Birth Control works by telling you which days are high risk for pregnancy so that you can use a barrier method such as a condom every time you have sex that may result in pregnancy. These methods prevent sperm from uniting with an egg, fertilizing it, and leading to pregnancy. Clue Birth Control has no side effects and does not interfere with your body’s natural menstrual cycle. 

Clue Birth Control has a similar typical use efficacy rate as some forms of hormonal birth control, but is less effective than others, especially IUDs, the shot, and the implant (1, 2). Remember that Clue Birth Control requires daily participation from you. Birth control pills require that you take them every day, but some methods like the patch or the ring are effective without daily participation.Talking to your healthcare provider about the risks and benefits of each method of contraception may help you choose which one is right for you. See the chart below for the typical and perfect use efficacy rates for each method. 

A table depicting the efficacy of different birth control methods

How does Clue Birth Control compare to other types of non-hormonal birth control?

Non-hormonal birth control options include the copper IUD and barrier methods like the condom, cervical cap, diaphragm, sponge, and surgical permanent sterilization (3). The most effective forms of non-hormonal birth control are the copper IUD and sterilization which are “set-it-and-forget-it methods”, meaning they are procedures that you don’t have to think about again (2). External condoms are the barrier method with the lowest risk of pregnancy — they are 87% effective with typical use and 98% effective with perfect use (2). You can read more about non-hormonal birth control here.

Fertility awareness based methods are also non-hormonal forms of birth control (4). FABMs work by identifying the fertile period during the menstrual cycle, so that you can abstain or use protection on fertile days to prevent pregnancy (4). Clue Birth Control is a FABM. Some other forms of FABMs are the Standard Days method, the cervical mucus method, the basal body temperature method (BBT), and the symptothermal method (4). 

There is a misperception that FABMs are not effective because research surrounding them is complicated (3). The effectiveness of these methods is often reported incorrectly because all the methods get grouped together, when some have higher or lower efficacy than others. Further, some methods have been studied individually and some have not. For those that have been studied, the research is often far from perfect. In some clinical trials, participants were excluded if they had difficulty learning how to use the method or if they had behavior that made them more of a typical than perfect user (5). Clue Birth Control is different because it was studied individually in a rigorous clinical trial (1) and it is cleared by the FDA. 

Clue Birth Control is more effective than some non-hormonal methods and only requires you to enter your period start date and check the app before having sex that could result in pregnancy. You need to use a barrier method such as a condom if it’s a high risk day. Other FABMs may have varying levels of efficacy depending upon how well you can use them—all require daily participation, but some can be more complicated or time consuming to use correctly. For example, some require daily documentation of additional biomarkers like cervical mucus, basal body temperature, or hormone levels (2, 4). The calendar method, also called the rhythm method, only requires tracking of cycle length. When using this method, it can be complicated to calculate the time when pregnancy can occur. People often misinterpret how to use it or use it incorrectly, so it is considered the least effective non-hormonal method (5, 2). Clue Birth Control doesn’t require you to do any calculations and determines your high risk days for pregnancy using just your period start dates. 

If you’re interested in non-hormonal contraception, talking to your healthcare provider about the risks and benefits of each method may help you choose which one is right for you. See the chart below for the typical and perfect use efficacy rates for each non-hormonal method. 

A table displaying non-hormonal birth control methods

Will Clue Birth Control be effective for me?

There are a few reasons Clue Birth Control might not be a good choice of contraception for you. If your cycles are shorter than 20 days or longer than 40 days, or if your cycle lengths vary by more than 9 days, Clue Birth Control can’t make a prediction about high risk and low risk days. This doesn’t mean there’s a problem with your cycles—cycles can vary and your body is not a clock. You can still use the Clue Period Tracking mode to track your cycle and cycle experiences.

If you’ve recently been on hormonal birth control, had the copper IUD, or were pregnant or breastfeeding, you will have to wait for 3 cycles (4 periods) before using Clue Birth Control. 

If you meet all the requirements to use Clue Birth Control, enter your most recent period start date to predict your daily risk of pregnancy for the current cycle. Check the app each day to instantly know if your risk of pregnancy is high or low. On high risk days you must use a barrier method such as a condom every time you have sex that may result in pregnancy. Always follow these instructions, and Clue Birth Control will be 97% effective. 

*In the interest of providing easy-to-understand information that empowers people to make informed health decisions, when reporting efficacy figures, Clue uses the upper bound of the failure rate’s 95% confidence interval. Clinical trial results represent an estimate of the population efficacy rate. To be conservative, Clue reports the upper bound of the confidence interval from the peer-reviewed, published clinical trial of Clue Birth Control rather than the point estimate.The clinical trial found a point estimate with confidence intervals for the typical-use failure rate of 5.8% (95% confidence interval: 3.6% - 8.1%). The point estimate with confidence intervals for perfect use failure rate was 1.0% (95% confidence interval: -0.9% - 2.9%). Therefore, the marketed efficacy rates are 92% effective with typical use and 97% effective with perfect use. The Clue Birth Control clinical trial was conducted by researchers at Georgetown University in Washington, DC, and is registered at ClinicalTrials.gov as study number NCT02833922.

Clue Birth Control will be launched in the USA in 2022. We are excited to bring Clue Birth Control to other countries soon. This will take a little more time, but we’re on it.

An illustration of a hand pressing a button

Let's support one another.

and champion menstrual health together. Make an impact today in one click.

An illustration of a hand pressing a button

You might also like to read

photo of a splash of water on top of a blue and teal square

Your Vagina

Getting wet: discharge vs. cervical fluid vs. arousal fluid

Are vaginal fluids really all that different? In this article, we explain how to identify vaginal discharge, arousal fluid, and cervical fluid.

Popular Articles