The Science Behind Our Birth Control Effectiveness

Discover the data behind the first and only birth control app. Our mission is to pioneer women’s health with research and passion, read on to find out how we make it happen with the science behind our birth control effectiveness.

What does research look like at Natural Cycles?

Natural Cycles is 93% effective with typical use and 98% effective with perfect use. Our birth control effectiveness comes from an analysis of over 15,000 women. The study looked at all possible reasons women become pregnant when using Natural Cycles. This includes having unprotected sex on a red day, to the app wrongly giving a green day, to a condom breaking. 

Did you know that we have a dedicated team committed to research? We regularly contribute with scientific involvement in the historically overlooked area of fertility and women’s health. Check out our published studies on Natural Cycles below:

  1. Perfect-use and typical-use Pearl Index of a contraceptive mobile app
  2. Fertility awareness-based mobile application for contraception
  3. Short- and long-term effect of contraceptive methods on fecundity
  4. Real-world menstrual cycle characteristics of more than 600,000 menstrual cycles
  5. Typical use effectiveness of Natural Cycles: postmarket surveillance study investigating the impact of previous contraceptive choice on the risk of unintended pregnancy
  6. Advantages of determining the fertile window with the individualised Natural Cycles algorithm over calendar-based methods
Decorative pink pie chart graphic showing the figure "93%"

Birth control effectiveness table

Birth Control Method
Phone with the natural cycles app and thermometer
Natural Cycles
Two contraceptive pill strips
illustration of a male condom
Male Condom
hormonal iud illustration
Illustration of NuvaRing
illustration of a calendar with some days crossed out
Fertility Awareness
hand with crossed fingers
Withdrawal Method
*Typical use %
*Perfect use %

*Percentage of typical/perfect users who did not get pregnant with the method over 1 year of use.

Reference: Contraceptive Technology (Table 26 - 1). 21st Edition, 2018 —>
Source: Trussell J . Contraceptive Efficacy. In Hatcher R A, Trussell J, Nelson A L , Cates W, Kowal D, Policar M. Contraceptive Technology: New York NY: Ardent Media, 2018—>

What is perfect use?

  • 98% effective means that 2 women out of 100 will get pregnant during 1 year of use, even with using the app perfectly
  • Perfect use is when you do not have unprotected sex on red days, i.e. always use a condom or abstain from sex
  • To be a perfect user, you do not need to measure every day at the same time, but you do need to use protection on every red day
  • Perfect use also includes women who had unprotected sex on a green day that was falsely given, or had protected sex on a red day but the method failed (e.g. a broken condom)

What is typical use?

  • Typical use shows how many women on average get pregnant due to all possible reasons
  • The most common reason for pregnancy with Natural Cycles is the failure to use protection on red days
  • Typical use includes pregnancies that occurred under perfect use
  • 93% effective under typical use means that 7 out of 100 women will get pregnant during one year of use


We are proud to work with leading medical advisors who bring their extensive knowledge and backgrounds in female health to Natural Cycles.

Dr. Helena Kopp Kallner

PhD. M.D.

A Senior Consultant in Obstetrics and Gynaecology at Danderyd Hospital and researcher at the Karolinska Institute, Dr Kopp Kallner is secretary of the Board of the Swedish Society of Obstetricians and Gynecologist. She is also a member of the Advisory Board of Natural Cycles. Dr Kopp Kalner works with Natural Cycle in designing and performing new research on fertility monitoring, contraception and mHealth.

FDA Cleared

In 2018 the US Food and Drug Administration (FDA) cleared Natural Cycles as a medical device for use as a digital method of birth control.

Certified in Europe

In Europe, Natural Cycles is the first CE-marked Class II medical device (CE0123) for use as a method of birth control.

Quality Regulated

We are ISO13485 certified, working to the highest level of safety and quality, with a quality management system at our core.


Discover Natural Cycles today