Flo Health

Consumer app for tracking menstrual cycles, ovulation, pregnancy and perimenopause symptoms.

At a glance

Headquarters: London, United Kingdom
Founded: 2015
Business model: B2C
Stage: Series C
Products profiled: 1
Operating markets: United Kingdom, United States
Sources cited: 3
In the library since: 16 September 2026

What it does

Flo is a cycle-tracking application. Users log symptoms and dates, and the app predicts the next period and fertile window, tracks a pregnancy, and more recently follows perimenopause symptoms.

Read the full description

Cycle tracking is one of the few categories where a consumer health app holds data that is both routinely collected and unusually sensitive. What a user records is enough to infer pregnancy, pregnancy loss and contraceptive use, which makes the handling of that data a product decision rather than a compliance footnote.

That is not a hypothetical here. In January 2021 the US Federal Trade Commission alleged that Flo had shared health data from users of its period and ovulation tracker with marketing and analytics firms including Facebook and Google, despite promising to keep it private. Flo settled without admitting the allegations, and in June 2021 the FTC finalised a consent order requiring the company to obtain affirmative consent before sharing health information, to notify affected users, to instruct third parties that received the data to destroy it, and to obtain an independent review of its privacy practices. The allegations were never tested in court; the order is final and binding.

The company reports very large download and active-user figures. Those are self-reported and are recorded here as the company's own numbers.