This article covers the following topics. To jump to a specific section, click on the links in the table of contents:
- Overview
- New users and NC° Birth Control effectiveness
- What about irregular cycles?
- When will I get Green Days?
- Important tips to remember when using NC° Birth Control
Overview
NC° Birth Control is the Natural Cycles mode that you can use to prevent pregnancy.
To use NC° Birth Control, you need to measure your body temperature, input your data, and then the Natural Cycles algorithm will provide your daily fertility status. Your fertility status will show as either a Green Day or a Red Day. Green Days mean that you’re not fertile. On Red Days, there’s a chance that you are fertile, and you should abstain or use condoms during intercourse to prevent pregnancy.
When using NC° Birth Control, in addition to seeing your daily fertility status, you can add extra information like cycle symptoms, mood changes, and sex data to learn even more about the pattern of your unique cycle.
You will also be able to log ovulation test results, which, although optional, may lead to higher ovulation day accuracy and more Green Days. LH levels surge 24-48 hours prior to ovulation, triggered by the increase in levels of estrogen in the body. Therefore, your LH level can be a good indicator of the most fertile days in the cycle. Ovulation tests measure the level of LH in urine and can be bought in the app, webshop, or your local pharmacy.
The picture above shows the Add data page, where you can log your temperature, period data, cycle symptoms, changes to your mood, and log if you took an optional ovulation test.
The Tracker graph lets you compare what cycle symptoms you've logged over time, so that you can spot patterns in your cycles.
To help you learn more about your body, the app can also send you reminders. For example, if you are using the PMS tracker in the app, you can receive PMS alerts. You can also get reminders about when to carry out a breast self-examination, as shown in the picture below:
New users and NC° Birth Control effectiveness
If you’re a new user of NC° Birth Control, it’s important to note that NC° Birth Control is effective from the first day of use (93% effective with typical use and 98% effective with perfect use). For the first cycles, when the algorithm doesn't have much information about when you usually ovulate and how much that varies, the buffer of Red Days at the beginning of the cycle is larger, and it will also need more data in order to confirm ovulation.
The more data you add over time, the more Green Days the NC° algorithm will be able to give you, as it will only produce a Green Day if it has enough information to confirm that you are not fertile. You will be given Red Days if the algorithm is uncertain.
What about irregular cycles?
Thanks to all the data you add to the app, Natural Cycles will get to know you and your unique cycle and adapt accordingly. You may experience more Red Days if you have irregular cycles, but the algorithm's effectiveness is the same.
When will I get Green Days?
You will get Green Days (non-fertile) before ovulation until the algorithm deems it possible that you could be approaching your fertile window. At that point, you will be given Red Days until the algorithm is able to confirm that you have ovulated. The NC° algorithm uses your past ovulation pattern combined with statistical analysis to determine the fertility status at the beginning of your cycle. The NC° algorithm will give a buffer of Red Days before the predicted ovulation based on several factors like sperm survival probabilities, your personal ovulation pattern, how regular your ovulation pattern is, and how much data has been collected from past cycles.
Once the algorithm has enough data to support that you have ovulated this cycle and that you have passed your fertile window, you will receive Green Days.
Important tips to remember when using NC° Birth Control
- Make sure that you’ve selected the NC° Birth Control mode. NC° Birth Control and NC° Plan Pregnancy work slightly differently. Detecting ovulation is the same for both products, but there are differences in the risk profile. For NC° Birth Control, the algorithm is optimized to have a very low risk of wrongly attributing a Green (safe) Day in the fertile window. In contrast, NC° Plan Pregnancy is optimized to better isolate the fertile window and the most fertile days. While using NC° Birth Control, the user gets either Green (non-fertile) or Red (use protection) Days. On the other hand, NC° Plan Pregnancy users get a fertility scale ranging from green (not fertile) to the darkest shade of red (peak fertility). In short, if you’re looking to prevent pregnancy, make sure that you’re using NC° Birth Control which is set up to help you do so.
- If you’re coming from hormonal contraception, you must finish it before starting NC°. The hormones in hormonal contraception, whether it's the pill, patch, shot, or hormonal IUD, usually work to inhibit ovulation. Please refer here to when you can start using Natural Cycles after quitting hormonal birth control.
- Check your fertility status each day in the Today view. Predictions update each day with new data. The NC° algorithm initially makes predictions based on previous cycle lengths, but the predictions are updated after ovulation has been detected in the current cycle to give more accurate cycle length predictions, using the ovulation date in the current cycle and your personal luteal phase length. Therefore, checking your fertility status in the Today view before intercourse is necessary to prevent pregnancy.
- Use additional contraception (we recommend condoms) or abstain from sex on Red Days. We regularly follow up on actual data from real users to monitor the Natural Cycles’ effectiveness and the algorithm’s performance. This is part of the post-market surveillance that we need to do as a certified medical device manufacturer for contraception. Every month we look at the effectiveness, unintended pregnancies, and the reasons behind the pregnancies. The most common reason for pregnancy using Natural Cycles is unprotected sex (including withdrawal) on a Red Day.
For a more detailed explanation of how Natural Cycles works, please visit this article.