Natural Cycles

K250561 · Natural Cycles Nordic AB · PYT · Mar 21, 2025 · Obstetrics/Gynecology

Device Facts

• Record ID: K250561
• Device Name: Natural Cycles
• Applicant: Natural Cycles Nordic AB
• Product Code: PYT · Obstetrics/Gynecology
• Decision Date: Mar 21, 2025
• Decision: SESE
• Submission Type: Special
• Regulation: 21 CFR 884.5370
• Device Class: Class 2
• Attributes: Software as a Medical Device

Intended Use

Natural Cycles is a stand-alone software application, intended for women 18 years and older, to monitor their fertility. Natural Cycles can be used for preventing a pregnancy (contraception) or planning a pregnancy (conception).

Device Story

Natural Cycles is a web and mobile-based standalone software application for fertility monitoring. Users input daily basal body temperature (BBT) via oral thermometer or compatible wearable devices (e.g., Oura Ring, Apple Watch), menstruation cycle data, and optional ovulation/pregnancy test results. A proprietary algorithm processes this data to determine daily fertility status. The device operates in three modes: Contraception (NC° Birth Control), Conception (NC° Plan Pregnancy), and Pregnancy (NC° Follow Pregnancy). In Contraception mode, it provides daily fertility status (fertile/red vs. non-fertile/green) to guide contraceptive use. In Conception mode, it displays fertility status to assist in timing intercourse. In Pregnancy mode, it provides educational information. Used in the home environment by the patient. The output informs user decision-making regarding pregnancy prevention or planning.

Clinical Evidence

No clinical data or performance testing was required for this submission as there were no changes to the device technology or identified risks.

Technological Characteristics

Standalone software application; web and mobile-based. Inputs: manual or automatic (wearable) BBT, cycle dates, test results. Outputs: fertility status (fertile/non-fertile), ovulation date, educational content. No changes to underlying technology from predicate.

Indications for Use

Indicated for women 18+ to monitor fertility for contraception or conception. Contraindicated for women with medical conditions where pregnancy poses significant risk to mother or fetus. Note: higher pregnancy risk for those using hormonal birth control within 60 days prior to use.

Regulatory Classification

Identification

A software application for contraception is a device that provides user-specific fertility information for preventing a pregnancy. This device includes an algorithm that performs analysis of patient-specific data (e.g., temperature, menstrual cycle dates) to distinguish between fertile and non-fertile days, then provides patient-specific recommendations related to contraception.

Special Controls

1. Clinical performance testing must demonstrate the contraceptive effectiveness of the software in the intended use population. 2. Human factors performance evaluation must be provided to demonstrate that the intended users can self-identify that they are in the intended use population and can correctly use the application, based solely on reading the directions for use for contraception. 3. Software verification, validation, and hazard analysis must be performed. Documentation must include the following: a. A cybersecurity vulnerability and management process to assure software functionality; and b. A description of the technical parameters of the software, including the algorithm used to determine fertility status and alerts for user inputs outside of expected ranges. 4. Labeling must include: The following warnings and precautions: a. i. A statement that no contraceptive method is 100% effective. ii. A statement that another form of contraception (or abstinence) must be used on days specified by the application. iii. Statements of any factors that may affect the accuracy of the contraceptive information. iv. A warning that the application cannot protect against sexually transmitted infections. b. Hardware platform and operating system requirements. Instructions identifying and explaining how to use the software application, including C. required user inputs and how to interpret the application outputs. d. A summary of the clinical validation study and results, including effectiveness of the application as a stand-alone contraceptive and how this effectiveness compares to other forms of legally marketed contraceptives.

*Classification.* Class II (special controls). The special controls for this device are:(1) Clinical performance testing must demonstrate the contraceptive effectiveness of the software in the intended use population. (2) Human factors performance evaluation must be provided to demonstrate that the intended users can self-identify that they are in the intended use population and can correctly use the application, based solely on reading the directions for use for contraception. (3) Software verification, validation, and hazard analysis must be performed. Documentation must include the following: (i) A cybersecurity vulnerability and management process to assure software functionality; and (ii) A description of the technical parameters of the software, including the algorithm used to determine fertility status and alerts for user inputs outside of expected ranges. (4) Labeling must include: (i) The following warnings and precautions: (A) A statement that no contraceptive method is 100% effective. (B) A statement that another form of contraception (or abstinence) must be used on days specified by the application. (C) Statements of any factors that may affect the accuracy of the contraceptive information. (D) A warning that the application cannot protect against sexually transmitted infections. (ii) Hardware platform and operating system requirements. (iii) Instructions identifying and explaining how to use the software application, including required user inputs and how to interpret the application outputs. (iv) A summary of the clinical validation study and results, including effectiveness of the application as a stand-alone contraceptive and how this effectiveness compares to other forms of legally marketed contraceptives.

Predicate Devices

• Natural Cycles (K231274)

Submission Summary (Full Text)

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Image /page/0/Picture/0 description: The image contains the logos of the Department of Health and Human Services and the Food and Drug Administration (FDA). The Department of Health and Human Services logo is on the left, and the FDA logo is on the right. The FDA logo includes the letters "FDA" in a blue square, followed by the words "U.S. FOOD & DRUG ADMINISTRATION" in blue text.

March 21, 2025

NaturalCycles Nordic AB Megan Callanan US and Global Regulatory Lead Sankt Eriksgatan 63 B Stockholm, 112 34 SWEDEN

Re: K250561

Trade/Device Name: Natural Cycles Regulation Number: 21 CFR 884.5370 Regulation Name: Software Application for Contraception Regulatory Class: II Product Code: PYT Dated: February 25, 2025 Received: February 25, 2025

Dear Megan Callanan:

We have reviewed your section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (the Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database available at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device"

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(https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download).

Your device is also subject to, among other requirements, the Quality System (QS) regulation (21 CFR Part 820), which includes, but is not limited to, 21 CFR 820.30. Design controls; 21 CFR 820.90. Nonconforming product; and 21 CFR 820.100, Corrective and preventive action. Please note that regardless of whether a change requires premarket review. the OS regulation requires device manufacturers to review and approve changes to device design and production (21 CFR 820.30 and 21 CFR 820.70) and document changes and approvals in the device master record (21 CFR 820.181).

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reportingcombination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050.

All medical devices, including Class I and unclassified devices and combination product device constituent parts are required to be in compliance with the final Unique Device Identification System rule ("UDI Rue"). The UDI Rule requires, among other things, that a device bear a unique device identifier (UDI) on its label and package (21 CFR 801.20(a)) unless an exception or alternative applies (21 CFR 801.20(b)) and that the dates on the device label be formatted in accordance with 21 CFR 801.18. The UDI Rule (21 CFR 830.300(a) and 830.320(b)) also requires that certain information be submitted to the Global Unique Device Identification Database (GUDID) (21 CFR Part 830 Subpart E). For additional information on these requirements, please see the UDI System webpage at https://www.fda.gov/medical-device-advicecomprehensive-regulatory-assistance/unique-device-identification-system-udi-system.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.

For comprehensive regulatory information about mediation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See

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the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email ([e-mail]) or phone [phone] or 301-796-7100).

Sincerely,

# Monica D. Garcia -S

Monica D. Garcia, Ph.D. Assistant Director DHT3B: Division of Reproductive, Gynecology, and Urology Devices OHT3: Office of Gastrorenal, ObGyn, General Hospital, and Urology Devices Office of Product Evaluation and Quality Center for Devices and Radiological Health

Enclosure

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| Indications for Use | | | |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------|
| Please type in the marketing application/submission number, if it is known. This textbox will be left blank for original applications/submissions. | K250561 ? | | |
| Please provide the device trade name(s). | ? | | |
| | Natural Cycles | | |
| Please provide your Indications for Use below. | ? | | |
| Natural Cycles is a stand-alone software application, intended for women 18 years and older, to monitor their fertility.<br>Natural Cycles can be used for preventing a pregnancy (contraception) or planning a pregnancy (conception). | | | |
| Please select the types of uses (select one or both, as applicable). | <table border="0"><tr><td><span style="text-decoration: overline;">X</span> Prescription Use (Part 21 CFR 801 Subpart D) </td></tr><tr><td><span style="text-decoration: overline;">X</span> Over-The-Counter Use (21 CFR 801 Subpart C) </td></tr></table> ? | <span style="text-decoration: overline;">X</span> Prescription Use (Part 21 CFR 801 Subpart D) | <span style="text-decoration: overline;">X</span> Over-The-Counter Use (21 CFR 801 Subpart C) |
| <span style="text-decoration: overline;">X</span> Prescription Use (Part 21 CFR 801 Subpart D) | | | |
| <span style="text-decoration: overline;">X</span> Over-The-Counter Use (21 CFR 801 Subpart C) | | | |

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# 510(k) Summary

# K250561 - Natural Cycles

| Applicant: | NaturalCyles Nordic AB<br>Sankt Eriksgatan 63B<br>Stockholm, Sweden 112 34 |
|------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Applicant<br>Contact: | Name: Megan Callanan<br>Phone: [phone]<br>Email: [e-mail] |
| Date Prepared: | March 20, 2025 |
| Trade Name: | Natural Cycles |
| Common Name: | Software application for contraception |
| Regulatory Class: | II |
| Regulation<br>Name: | Software application for contraception |
| Regulation<br>Number: | 21 CFR 884.5370 |
| Product Code: | PYT (Device, fertility diagnostic, contraceptive, software application) |
| Predicate Device: | K231274 Natural Cycles<br>The predicate device has not been subject to a design-related recall. |
| Device<br>Description: | Natural Cycles is an over-the-counter and prescription web and<br>mobile-based standalone software application that monitors a<br>woman's menstrual cycle using information entered by the user and<br>informs the user about her past, current and future fertility status.<br>The following information is used by the Natural Cycles software:<br>daily temperature measurements, information about the user's<br>menstruation cycle (i.e., start date, number of days), and optional<br>ovulation or pregnancy test results. A proprietary algorithm evaluates<br>the data and returns the user's fertility status. Users can choose to<br>use Natural Cycles in various modes based on their goals.<br><br>Natural Cycles is available in three modes: Contraception (NC° Birth<br>Control), Conception (NC° Plan Pregnancy), and Pregnancy (NC°<br>Follow Pregnancy). For NC° Birth Control mode, the device provides<br>predictions of "not fertile," shown as green days, and "use<br>protection," shown as red days, that allow the user to determine the<br>days on which her risk of conception is highest, and then make |
| | contraception to prevent pregnancy.<br><br>Inputs to the device include user-inputted daily basal body temperature measured with an oral thermometer with two decimal points or a compatible wearable device (e.g., Oura Ring and Apple Watch).<br><br>Natural Cycles can be used by women 18 years and older. Women who have been on hormonal birth control within 60 days prior to using Natural Cycles have a higher risk of becoming pregnant when compared to women who have not been on hormonal birth control within the 12 months prior to using the device. This device may not be right for women who have a medical condition where pregnancy would be associated with a significant risk to the mother or the fetus |
| Indications for Use: | Natural Cycles is a stand-alone software application, intended for women 18 years and older, to monitor their fertility.<br>Natural Cycles can be used for preventing a pregnancy (contraception) or planning a pregnancy (conception). |

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## Summary of Technical Characteristics:

The technology of the Natural Cycles Application is identical to the predicate device.

| Parameter | Predicate Device Natural<br>Cycles<br>K231274 | Subject Device<br>Natural Cycles<br>K250561 | Comparison |
|----------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Indications for<br>Use Statement | A stand-alone software<br>application, intended for<br>women 18 years and older,<br>to monitor their fertility.<br>Natural Cycles can be used<br>for preventing a pregnancy<br>(contraception) or planning a<br>pregnancy (conception). | A stand-alone software<br>application, intended for<br>women 18 years and older,<br>to monitor their fertility.<br>Natural Cycles can be used<br>for preventing a pregnancy<br>(contraception) or planning a<br>pregnancy (conception). | Same |
| Use<br>Environment | App is downloaded to<br>user's smartphone and<br>used in the home<br>environment | App is downloaded to<br>user's smartphone and<br>used in the home<br>environment | Same |
| Type of Use | Over-The-Counter Use | Prescription Use and<br>Over-The-Counter Use | Different – The change<br>from over-the-counter<br>to both over-the-<br>counter and<br>prescription use does<br>not raise different<br>questions of safety and<br>effectiveness. |
| Input<br>Information | ● Manual input of<br>two-decimal daily<br>basal body<br>temperature (BBT)<br>measurements or<br>automatic input from a<br>validated third party<br>temperature measuring<br>device.<br>● Manual input of<br>information about the<br>user's menstruation<br>cycle, i.e. start date,<br>number of days.<br>● Optional manual input<br>of ovulation or<br>pregnancy test results. | ● Manual input of<br>two-decimal daily<br>basal body<br>temperature (BBT)<br>measurements or<br>automatic input from a<br>validated third party<br>temperature measuring<br>device.<br>● Manual input of<br>information about the<br>user's menstruation<br>cycle, i.e. start date,<br>number of days.<br>● Optional manual input<br>of ovulation or<br>pregnancy test results. | Same |
| Output<br>Information | • NC° Birth Control mode:<br>For each day, whether the<br>woman is fertile (red) or<br>non-fertile (green), with<br>descriptive texts.<br>• NC° Plan Pregnancy mode:<br>Fertility status results are<br>displayed as a scale for<br>fertile days, and green for<br>non-fertile days, together<br>with description texts.<br>• NC° Follow Pregnancy<br>mode: Provides<br>educational information<br>about the progress of<br>the pregnancy. | • NC° Birth Control mode:<br>For each day, whether the<br>woman is fertile (red) or<br>non-fertile (green), with<br>descriptive texts.<br>• NC° Plan Pregnancy mode:<br>Fertility status results are<br>displayed as a scale for<br>fertile days, and green for<br>non-fertile days, together<br>with description texts.<br>• NC° Follow Pregnancy<br>mode: Provides<br>educational information<br>about the progress of<br>the pregnancy. | Same |
| | All users in NC° Birth Control<br>mode or NC° Plan Pregnancy<br>mode receive the ovulation<br>date for the month and daily<br>statement of fertility status.<br>Historic data is available for<br>all users. | All users in NC° Birth Control<br>mode or NC° Plan Pregnancy<br>mode receive the ovulation<br>date for the month and daily<br>statement of fertility status.<br>Historic data is available for<br>all users. | |

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## Discussion of Differences

As outlined in the table above, the subject and predicate device have identical indications for use statements. The devices differ in the inclusion of prescription use as well as over-the-counter use for the subject device. No changes have been made to the device technology, meaning there are no differences between Natural Cycles cleared under K231274 and the proposed device. The change to prescription and over-the-counter use does not raise different questions of safety and effectiveness.

## Summary of Non-Clinical Performance Testing

There have been no changes to the technology of the device, and no new risks or increased likelihood or magnitude of identified risks have been introduced due to the change from over-the-counter to prescription and over-thecounter use. Therefore, no performance data is needed to validate this change.

## Conclusion

The information outlined above is sufficient to demonstrate that the subject device (Natural Cycles) is as safe and effective as the predicate device and supports a determination of substantial equivalence.