Flo vs Natural Cycles: Data Broker vs FDA-Cleared Contraception
TLDR
Natural Cycles is an FDA-cleared contraceptive app built around basal body temperature tracking — a fundamentally different product than Flo. Flo settled a $59.5M class action in 2025 for sharing reproductive health data without consent. Both apps require an account and server-side storage.
| Feature | Flo | Natural Cycles | Floriva |
|---|---|---|---|
| FDA-cleared contraception | No | Yes (De Novo 2018) | No |
| Temperature tracking | Optional | Required | Yes |
| On-device storage | No | No | Yes |
| Account required | Yes | Yes | No |
| FTC enforcement history | Yes (2021) | No | No |
| Data can be subpoenaed | Yes | Yes | No |
| Price | Free / $4.99/mo | $12.99/mo | $2.99/mo |
Two different products competing in the same category
Flo is a general-purpose period and symptom tracker. Natural Cycles is an FDA-cleared contraceptive device that happens to be an app. Comparing them requires understanding that distinction.
If contraception is your primary goal, Natural Cycles is the only app in this category with FDA De Novo clearance for contraceptive use. That clearance means the FDA reviewed clinical evidence for effectiveness — something no other period tracker has done. The trade-off is cost ($12.99/mo) and daily commitment (basal body temperature every morning before getting up).
If general cycle tracking and symptom logging is your goal, Flo’s free tier covers the basics. But Flo’s data practices are a documented problem. The FTC found in 2021 that Flo shared health data with Facebook, Google, and Flurry without user consent. A class action over the same conduct settled for $59.5M in September 2025 (Reuters 2025-09-25).
The privacy gap neither closes
Both Flo and Natural Cycles require an account. Both store your data on company servers. Neither offers on-device-only architecture.
This matters because server-side storage means data exists somewhere that can receive a subpoena. In states with abortion restrictions, period data has been sought as evidence. GDPR compliance (Natural Cycles is Sweden-based) limits commercial misuse but does not prevent law enforcement access.
Floriva takes a different position: all data stays on your device. No account, no server, nothing to hand over. The FDA clearance for contraception that Natural Cycles holds is genuinely valuable — Floriva doesn’t offer that. But for cycle tracking without legal exposure, on-device architecture is the only structural protection available.
Cost breakdown
Natural Cycles is the most expensive option in the space at $12.99/mo or $99.99/yr. Flo Premium is $4.99/mo or $39.99/yr. Floriva is $2.99/mo. If you need FDA-cleared contraception, Natural Cycles’ price premium is justified. If you need cycle tracking and privacy, Floriva costs less than either and stores nothing on a server.
Neither feels private enough?
Floriva stores everything on your device. No data sold, no account required.
Verdict
Flo and Natural Cycles serve different use cases. If you need FDA-cleared contraception and are willing to track daily temperature, Natural Cycles is the only app in this space with that certification. If you need general cycle tracking without paying $12.99/mo, Flo's free tier is feature-rich — but comes with a documented data-sharing history. Neither offers on-device architecture.
PROS & CONS
Flo
Pros
- Free tier functional for basic tracking
- Broad symptom and mood logging
- Large user base improves predictions
Cons
- FTC-confirmed data sharing with Facebook and Google (2021)
- $59.5M class action settlement (2025)
- Server-based data with subpoena exposure
- Not suitable for contraception decisions
PROS & CONS
Natural Cycles
Pros
- FDA De Novo cleared for contraception
- Algorithm built on peer-reviewed fertility research
- No documented data-selling history
Cons
- Requires daily temperature measurement — not passive
- Most expensive period tracker at $12.99/mo
- Server-based — data accessible via legal process
- Effectiveness depends on consistent user behavior
PROS & CONS
Floriva
Pros
- On-device storage — nothing on servers to subpoena
- No account required
- $2.99/mo for all users
- Privacy is architecture, not policy
Cons
- Not FDA-cleared for contraception
- Smaller feature set at launch compared to established apps
Is Natural Cycles FDA approved?
Natural Cycles received FDA De Novo clearance in 2018 as a contraceptive app — the first digital contraceptive to receive this designation in the US. De Novo clearance means the FDA reviewed the clinical evidence and found the device to be safe and effective for its intended use. This is different from general FDA approval but represents meaningful regulatory oversight of the contraceptive claims.
Does Natural Cycles sell user data?
Natural Cycles has not faced the same FTC enforcement actions as Flo. The company is Sweden-based and operates under GDPR, which restricts commercial data sharing. However, Natural Cycles does require an account and stores data server-side, so the data exists on their servers and is theoretically accessible to law enforcement via court order.
What is the cheapest private period tracker?
Floriva is $2.99/mo with on-device-only storage and no account required. Euki and Drip (Android) are free and also use on-device storage. Natural Cycles is the most expensive at $12.99/mo and does not offer on-device architecture. Flo's free tier is functionally usable but carries a documented data-sharing history.
Frequently Asked Questions
Can I use Natural Cycles as birth control?
What happened with Flo and the FTC?
How much does Natural Cycles cost vs Flo?
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