Meet Dr. Jessica Shepherd,
MD, MBA, FACOG
Dr. Jessica Shepherd is a board-certified OB-GYN and member of the Natural Cycles Medical Advisory Board. Join the #1 birth control app backed by leading women’s health experts.
6+ milion users worldwide
Meet the NC° Medical Advisory Board
Dr. Barbara Levy
MD, FACOG, FACS, MSCP
NC° Medical Advisory Board
Dr. Karen Tang
MD, MPH, FACOG
NC° Medical Advisory Board
Comparison of contraceptive effectiveness
NC° Birth Control is more effective than calendar-based FABMs and is in the same effectiveness category as the pill.
NC° Birth Control
98% Perfect use
Percentage of typical/perfect users who did not get pregnant with the method over one year of use.
Reference: Contraceptive Technology (Table 5-2). 22nd Edition, 2023
It all starts with your temperature
What happens
Your temperature follows a pattern throughout your cycle, rising after ovulation due to hormonal changes.
Why it matters
You're only fertile during a short ~6 day window around ovulation. Most days of your cycle aren't fertile.
How NC° uses temperature
The NC° algorithm analyzes your temperature data to identify ovulation and predict fertile and non-fertile days.
Ovulation is the release of a mature egg from an ovary during the menstrual cycle. The egg survives for up to 24 hours after release.
Ovulation usually occurs around two weeks after your period begins, but the timing can vary from cycle to cycle.
The 6-day fertile window is determined by sperm and egg survival.
Sperm can survive for up to five days in the reproductive tract, and an egg survives for up to 24 hours after ovulation.
This means pregnancy is only possible during these six days.
Body temperature changes in response to hormonal shifts throughout the menstrual cycle. After ovulation, rising progesterone causes a small increase in temperature.
By tracking these changes over time, it's possible to identify cycle patterns, predict the fertile window, and confirm ovulation.
Natural Cycles works with compatible wearables to collect temperature data overnight, making it simple to track the subtle changes that occur throughout your cycle.
One app, more ways than ever to measure
NC° Band
No screen, no flashes, no beeps — just comfort-first measuring that’s cost-friendly.
Oura Ring
Premium, multipurpose wearable lets you track broader health metrics beyond fertility like sleep, stress, and activity.
Garmin
Advanced training metrics, plus fitness and recovery tracking, all in one stylish design.
WHOOP
Designed for lasting progress, with 24/7 health insights to help your sleep, training, and recovery.
Apple Watch
Tracks broader health metrics and displays your daily fertility status right on your wrist.
No
One app, more ways than ever to measure
NC° Band
No screen, no flashes, no beeps — just comfort-first measuring that’s cost-friendly.
Oura Ring
Premium, multipurpose wearable lets you track broader health metrics beyond fertility like sleep, stress, and activity.
Garmin
Advanced training metrics, plus fitness and recovery tracking, all in one stylish design.
WHOOP
Designed for lasting progress, with 24/7 health insights to help your sleep, training, and recovery.
| Compare devices | NC° Band | Oura Ring | Garmin | WHOOP | Apple Watch |
|---|---|---|---|---|---|
| Battery life | ~14 days | ~5-8 days | ~10 days | 14+ days | ~1-3 days |
| Where to measure | Inner wrist | Finger | Wrist | Wrist | Wrist |
| When to measure | Overnight | Overnight | Overnight | Overnight | Overnight |
| Automatic sync | Yes | Yes | Yes | Yes | Yes |
| NC° Sleep Insights | Yes | Yes | No | No | No |
| Subscription | NC° only | NC° and Oura | NC° only | NC° and WHOOP | NC° only |
| Special offer | No |
How to use Natural Cycles°
Wear a compatible device
Go to sleep
Wake up to insights
Missing an occasional temperature reading won't affect Natural Cycles' effectiveness as birth control. The NC° Fertility Algorithm is designed to prioritize safety and will adjust for missing data.
However, frequent missed readings can make it harder to identify your fertile window, resulting in more ‘Red Days’ where you will be advised to use protection or abstain from sex.
For the best experience, we recommend logging at least five temperatures per week.
Sleep Insights is a new feature in the NC° app that connects your nightly sleep data to your cycle phase, helping you better understand how hormonal changes may impact your rest and recovery.
Sleep Insights is currently available for NC° Band and Oura Ring users.
Your temperature may be excluded if it's considered less reliable — for example, due to illness, a hangover, unusual sleep patterns, or insufficient overnight wearable data. Excluded temperatures aren't used by the NC° Fertility Algorithm.
Missing or excluded temperatures won't affect the effectiveness of Natural Cycles, though missing temperature data may result in more ‘Red Days’ (where we recommend using protection) until enough reliable data is available again.
Powered by your biomarkers
Measure effortlessly overnight
with NC° Band.
Natural Cycles is also compatible with
Common questions
Natural Cycles is the first and only app of its kind cleared by the FDA as birth control. Most other fertility apps assume your cycle is 28 days long. This means the fertile window they predict is not personalized to your cycle. So, how can it be true to you? Our algorithm significantly reduces the risk of you receiving an incorrect fertility status since it uses your unique temperature data, which reduces the risk of unwanted pregnancy and can even help you plan for pregnancy with greater precision.
Plus, not all period trackers keep secrets — some might even share them. With the Natural Cycles app, your data stays yours. We provide an advanced data privacy protection program designed to keep your data safe. Find out why women around the world choose Natural Cycles.
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!
Birth control costs money to make and supply. A subscription to the Natural Cycles app helps make hormone-free birth control more accessible, giving you more choices to find what works for you — all while supporting women’s health research.
Because we charge a subscription, we don’t need to profit from selling users’ data like some “free” apps do. Natural Cycles is committed to data privacy, and as a regulated medical device, we are required to comply with the FDA’s cybersecurity requirements.
We offer two plans: annual or monthly. Click here to find the right subscription option for you.
Yes. The effectiveness of Natural Cycles is supported by clinical evidence, which shows Natural Cycles is 93% effective with typical use. When used as intended, 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!
How effective is NC° Birth Control?
98% when used as intended,
93% with typical use.
NC° is in the same effectiveness category as
the pill with zero side effects.
Condom
87%
NC°
93%
The Pill
93%
IUD
>99%
Typical use effectiveness rates. Source:
Contraceptive Technology (Table 5-2). 22nd Edition, 2023
Trusted by leading women’s health experts
Dr. Kerry Krauss
OB-GYN & Senior Medical Advisor at Natural Cycles
