Natural Cycles has secured its sixth clearance from the Food and Drug Administration, this time for an updated version of the algorithm that powers its birth control app. The company announced the approval of the next-generation NC° Fertility Algorithm on July 27, 2026, stating the update blends statistical modeling with machine learning trained on real-world fertility data. This new version aims to deliver more individualized fertility predictions for users.
Algorithm updates target better accuracy with existing data
The FDA approval confirms that the new software maintains the existing safety and effectiveness profile of the device while increasing the number of Green Days for many users. Green Days are the days on which the app indicates pregnancy protection is not needed. The update is intended to improve performance for individuals with irregular cycles and is designed to better process lower-quality temperature and biomarker data.
Effectiveness rates for the app remain high. Natural Cycles cites a 98% success rate with perfect use and 93% with typical use. These figures place the digital birth control method in the same effectiveness range as combined oral contraceptive pills, supported by peer-reviewed clinical research and real-world evidence.
One of the more complex aspects of fertility tracking is that a person’s cycle does not always follow a rigid schedule. As the body changes over time, the data patterns shift, making it difficult for older algorithms to keep up. The updated system is designed to learn and adapt more quickly as a user’s cycle changes, which helps smooth out the noise that often comes with irregular periods or inconsistent sensor readings. This adaptability reduces the margin of error when the input data is not perfectly clean, which is a common issue with wearable devices that sometimes lose connection or record inaccurate measurements.
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PCCP pathway enables hardware integrations
The path to this latest clearance involved a Predetermined Change Control Plan (PCCP), a regulatory strategy that creates a structured pathway for future updates. Natural Cycles used this framework to streamline the approval process for the machine learning components. The success of this pathway has enabled additional hardware integrations beyond the app itself.
The 2024 PCCP clearance has since supported the launch of the NC° Band, a wearable built specifically for the app, along with a hardware integration with Garmin that launched in March. The company has also received regulatory authorization in more than eight markets outside the United States, including Europe, Canada, Brazil, Australia, South Korea, and Singapore.
Natural Cycles will continue to develop the algorithm based on user feedback and emerging scientific research. The developers plan to refine the system further to handle the increasing volume of data generated by connected health devices. This ongoing evolution ensures the technology remains relevant as user needs change and as the broader health setting shifts.
