A Private Period Tracker App with Amber Vodegel of 28X | Blush & Bloom Podcast | Ep. 52

On this week's Blush & Bloom, Gigi Kenneth sits down with Amber Vodegel, the Dutch tech entrepreneur who founded and bootstrapped Pregnancy+ before selling it to Philips in 2017, and who now runs 28X, a free private period tracker app. Her argument is clear: health information should be free for every woman, and the data a woman logs about her body should stay on her own phone.

In This Episode, We Cover:

• How Pregnancy+ grew, in Amber's telling, to more than 150 million users without a marketing budget
• Bootstrapping a health app from personal savings, in the evenings, around a day job
• Why Amber is skeptical of "product-market fit" and builds for people instead
• How on-device AI lets 28X work with no cloud backend
• Why period app paywalls exist, and what a free app does differently
• A simple script for being heard by a GP about painful periods
• Moral Ambition, the book that kept her from retiring

Bootstrapping a health app to acquisition

Amber started Pregnancy+ with a few thousand pounds of savings, building it in the evenings around a full-time job and putting every bit of revenue back into the product. It grew across more than a hundred countries with no outside investment, mostly because women recommended a trustworthy app to other women.

Building for people, not markets

Amber does not chase product-market fit. When Pregnancy+ users sent in bump photos for a week-by-week series inspired by its most clicked article, "Is my belly big enough?", the backgrounds showed women of every age, income and culture. That changed the app's tone and content.

Why does a private period tracker app matter?

Because health data stored in the cloud can travel. Amber points to AI tools already screening job applicants and asks who gets hired or insured once that data is out there. "When all your data is online, who will get the job? The woman looking to get pregnant or the one who isn't?" 28X keeps everything on the device, so nobody sees what a user logs or reads.

How does on-device AI work in women's health apps?

28X runs its AI on the phone itself rather than on cloud servers, so there is no backend storing personal data. Amber says this was not possible when she built Pregnancy+. It also means serving one user or a hundred million costs about the same, which is what lets a privacy-first app stay free.

Why do so many period apps sit behind paywalls?

Amber traces period app paywalls back to funding. When some well-funded period-tracking apps take large amounts of venture capital, investors expect a big return, and the user ends up as the product through subscriptions, data sharing or selling items. She supports venture capital for research, but not for consumer health apps that most women cannot afford.

How a free app stays sustainable

28X has no subscriptions and does not sell data. Revenue comes from small streams that fit the mission: recruitment for clinical trials and stem cell donation, plus an optional, Wikipedia-style invitation to pay it forward. User feedback shapes the rest, from a choice of colours (people asked why all these apps are pink) to different reading levels and a discreet design.

Being heard at the doctor's office

Amber sees progress on endometriosis and menopause, but also a market keen to sell women gadgets they do not need. Clear language helps more. Instead of "I have bad periods," she suggests telling a GP your pain score, how it affects work or school, and that you do not think it is normal. Asele's Health Brief is built around the same idea of preparing for that conversation.

Moral Ambition and a 28X future

After her exit, Amber read Moral Ambition by Rutger Bregman and decided to build again rather than retire. Her five-year goal for 28X is a hundred million monthly active users, measured just as much by trust and reach among women in low-income countries. She also makes a case for a sugar tax, because "Happy people make healthy people," and good food should be affordable.

FAQ

Who is Amber Vodegel? Amber Vodegel is a Dutch tech entrepreneur and the founder of 28X, a free private period tracker. She previously founded and bootstrapped Pregnancy+, one of the world's most used pregnancy apps, which she sold to Philips in 2017.

What is 28X? 28X is a free period tracker app that uses on-device AI, so personal data stays on the user's phone instead of a cloud server. It has no subscriptions and does not sell data. It is available on the App Store and Google Play.

Why is it called 28X? Twenty-eight refers to the average length of a menstrual cycle, and the X is understood across most alphabets, so the name works in any language without translation.

Are free period tracker apps safe? It depends on where your data goes. Amber's view is that an app which stores nothing in the cloud cannot leak or share what it does not hold. Check whether an app processes data on your device or on its servers.

Listen and connect

Listen to the full conversation on Spotify, Apple Podcasts, or YouTube. Learn more about 28X at my28x.com. For more on trust and data in health tech, read our episodes on building trustworthy health tech and the gender data gap, and explore the Blush and Bloom podcast hub and Asele.

This episode is for general informational purposes and does not constitute medical, legal, or regulatory advice.