Natural Cycles is an app-based fertility tracking product that may help understand reproductive patterns and ovulation windows. The app relies on daily body temperature data and optional cycle inputs for fertility tracking. It requires you to take or sync a temperature measurement each morning, and the app integrates this with cycle history to generate personalized fertile and non-fertile day estimates. However, can Natural Cycles accurately estimate ovulation windows and prevent or predict pregnancy?
This review looks closely at how the app works, how the algorithm uses temperature data, and what daily use actually involves. It also covers real user experiences with the app, subscription structure, associated advantages, and potential limitations.
What Is Natural Cycles?
Co-founded by Elina Berglund and Raoul, the Natural Cycles app offers a non-hormonal means of birth control and fertility awareness that also supports pregnancy planning, postpartum recovery, and perimenopause tracking. It uses your biometric data, primarily basal or overnight body temperature, to identify fertile and non-fertile days.
As per its official site, temperature can be measured manually or collected through compatible devices. An FDA-cleared algorithm analyzes this data to determine ovulation patterns and daily fertility status, while optional in-app trackers allow you to log mood, energy, and other cycle-related factors.
The makers claim Natural Cycles follows GDPR requirements for data handling. Data is stored and processed using encrypted systems, with internal controls intended to limit access and reduce unauthorized use. System audits and security checks are part of its operational structure.
How Does It Work?
As per the makers, Natural Cycles works by analyzing daily body temperature data to identify changes in your menstrual cycle and estimate fertile windows. The process starts with measuring your temperature overnight, since resting temperature patterns shift around ovulation. Such measurements are collected automatically through compatible devices, like the NC° Band, Apple Watch, or Oura Ring. The idea is to capture consistent, real-world data without relying on manual temperature readings each morning.
Depending on your goal, the daily status can be used to decide when protection is needed or when conditions may be more favorable for conception. Alongside fertility status, the app also allows tracking of cycle-related physical and emotional changes to provide a broader view of patterns over time. Natural Cycles also offers multiple modes within the same app, including birth control, planning pregnancy, following pregnancy, postpartum, and perimenopause.
Natural Cycles Advantages
Personalized Fertility Pattern Insights
Natural Cycles highlights fertility tracking based on individual data rather than generalized cycle assumptions. The system follows real hormonal changes in the body by using daily temperature readings and period start dates as the main inputs. Combining these inputs allows fertility predictions to reflect personal cycle patterns instead of population averages.
Personalized fertility tracking may be helpful when cycle lengths or ovulation timing tend to vary. Consistent tracking may provide clearer visibility into fertile timing, which can be useful when trying to better understand how individual cycles actually behave.
Daily Fertility Notifications
Natural Cycles presents day-by-day fertility status. You can enter temperature and period data daily. After each entry, the app generates an updated fertility status for that specific day, rather than relying on static predictions made earlier in the cycle.
Fertility notifications are shown through a simple color system. Red days are described as higher-fertility days, while green days are described as lower-fertility days. These notifications update daily as the algorithm reviews new temperature readings alongside past cycle data.
Natural Cycles states that these notifications function as clear daily signals that could make it easier to decide when to plan or avoid pregnancy based on personalized inputs. Daily updates are also more precise than calendar-based tracking methods that do not adjust in real time.
Established Regulatory First-Mover
Natural Cycles is positioned as an early regulatory entrant in the U.S. digital fertility tracking space. The official site highlights that the app became the first app cleared by the U.S. Food and Drug Administration in 2018. Such clearance may allow the app to be marketed specifically for contraception based on fertility monitoring rather than general cycle awareness. The product later received further FDA clearances through the 510(k) process. Such approvals allow app integration with external devices like Oura Ring and Apple Watch for temperature tracking, while maintaining FDA oversight as features expand.
Natural Cycles Limitations
Subscription Cost Required
Natural Cycles requires you to purchase a subscription, which places an immediate cost barrier on access. Although the app can be downloaded for free, daily fertility status, ovulation predictions, and algorithm-based insights remain unavailable without an active subscription.
The app includes both monthly and annual subscription plans. Monthly subscription options start at about $21.99 per month, while Reddit reviews indicate that the annual subscription costs are listed at around $149.99 per year, with regional pricing ranging from approximately $127 to $150.
Subscriptions renew automatically by default and must be canceled manually to avoid future charges. Refunds are usually not provided if cancellation occurs mid-cycle. As access to the app-based services depends on continuous payment, long-term use involves recurring expenses that may not align with your budget.
Strict Morning Temperature Required
Natural Cycles app requires you to take your lowest body temperature of the day, taken immediately after waking and before getting out of bed, talking, eating, drinking, or moving. This creates a narrow window for measurement and leaves little tolerance for routine variation.
Temperature readings are expected at roughly the same time every morning. Even small shifts in wake-up time or morning habits may alter results. The app’s algorithm depends on this level of consistency to detect ovulation and calculate fertile days. Common lifestyle factors can also interfere with tracking accuracy. Poor sleep, nighttime waking, travel across time zones, alcohol use, illness, or fever can raise or distort temperature readings.
Missing readings or logging inconsistent temperatures can delay ovulation confirmation. This may often result in more red days and fewer low-fertility days shown in the app. Accurate tracking depends on strict timing and consistency, so even minor disruptions may reduce clarity and lead to more conservative fertility predictions over time.
Pros
- Claims to use an FDA-cleared algorithm that personalizes fertility status using basal temperature data for accurate predictions.
- Supports multiple goals, including preventing pregnancy, planning conception, pregnancy tracking, and postpartum recovery.
- Integrates with Apple Watch and Oura Ring for easy daily tracking.
- App includes mood/energy logging, customized insights, and educational content to understand cycle impacts.
- Emphasizes backing of strong data privacy protections that prevent unauthorized sharing of data.
Cons
- Subscription-based model adds ongoing costs after the initial purchase.
- Effectiveness depends on accurate self-reported inputs and app usage.
How Did We Evaluate?
Brand Credibility
For evaluation, we analyzed the brand’s core background, positioning, and presence across independent review platforms. Natural Cycles presents itself as an established digital health brand that has expanded beyond basic ovulation cycle tracking to include integrations with wearable devices and broader fertility planning use cases.
On the Better Business Bureau, the brand maintains an F rating primarily driven by repeated complaints around subscription renewals, unexpected charges, limited refund flexibility, and difficulty accessing direct customer support. Across reviews and complaints, similar themes recur, with users noting unexpected charges after perceived cancellation, lack of advance renewal notices, and reliance on email or chat-based support.
TenereTeam provides Natural Cycles with a 4.6 out of 5 score based on over 2000 ratings on the platform. The profile indicates a high volume of users who view the app as useful, particularly for those committed to daily tracking and non-hormonal ovulation tracking methods. However, some users acknowledged limitations, including customer service inconsistencies, cost considerations, and refund and cancellation concerns.
Natural Cycles demonstrates credibility in terms of longevity, market presence, and user adoption, but this credibility is moderated by persistent concerns around subscription handling and customer support practices.
Real User Reviews
When evaluating Natural Cycles, we reviewed the available customer feedback on Trustpilot, where the platform holds a score of 4.2 out of 5, which is based on 1,740+ reviews. Most users reflect satisfaction with the app’s core purpose of ovulation cycle tracking and fertility awareness. However, there are some concerns raised around practical app limitations and subscription/billing practices.
Many users described using the app after stopping hormonal birth control and shared that it helped them better understand cycle timing, ovulation patterns, and physical or mood-related changes. Reviews often noted that predictions became clearer with continued use, especially when daily temperature data was logged consistently. Integration with wearable devices like smart rings or watches was mentioned as improving ease of use compared to manual temperature measurements.
However, some users with irregular cycles often reported that the app takes a more cautious approach, which resulted in more restricted fertile days and less flexibility. Manual temperature tracking was also described as difficult to maintain for those with inconsistent sleep routines, while others mentioned that older hardware versions were inconvenient or required replacement.
Feedback on customer support responsiveness is mixed, with some reviews indicating helpful responses while others expressing dissatisfaction with resolution speed or outcomes. Some users noted issues around automatic renewals, higher-than-expected annual charges, price increases, and limited refund options post-billing.
Based on the available feedback, most reviews present Natural Cycles as effective for fertility and cycle tracking when used correctly. However, dissatisfaction around pricing transparency, subscription management, and app-related issues indicates points of concern.
Frequently Asked Questions
No. It does not measure hormones directly. The app relies on daily basal body temperature (BBT) and cycle data to confirm ovulation after it occurs. You may optionally log urinary LH test results, but these are manually entered and not measured or analyzed by the app itself.
Yes. Factors like illness, alcohol use, stress, irregular cycles, or missed/inaccurate temperature entries may lead to inaccuracies, as predictions rely on consistent basal body temperature data. Such data disruptions might increase the risk of misidentified fertile days.
No. Natural Cycles is not compatible with hormonal contraceptives like the vaginal ring or patch. These methods suppress ovulation and alter natural temperature patterns, which prevents the app from reliably interpreting basal body temperature data. The makers advise discontinuing hormonal contraception and allowing cycles to normalize before using the app.
Conclusion
Natural Cycles offers additional support for fertility and ovulation tracking. However, its approach depends on daily tracking and long-term pattern recognition, making accuracy closely tied to routine consistency rather than automation.
Performance remains sensitive to individual variability and adherence requirements. The effectiveness of app predictions may decline with irregular cycles, higher stress levels, disrupted sleep, or inconsistent measurement timing. Early use often involves more fertile-day restrictions while sufficient data is established, which may impact practical usability.
When opting for Natural Cycles, some practical considerations and limitations may impact suitability for your needs. For instance, it does not offer protection against sexually transmitted infections, and use requires an ongoing subscription commitment. Reviewing cycle regularity, comfort with daily tracking, and discussing your medical history with a doctor remains an important step before opting for the product.
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Alisha Matthew has been a practicing nutritionist since 2016. She holds a master’s degree in nutrition from the University of IOWA. She is a staunch believer in improving the human health index by educating people about nutrition and the importance of nutrition in leading a healthy and happy life. Her long-term goal is to keep educating people on general health and keep herself updated with the latest trends in the field of health.