The Do's and Don'ts of FemTech
Not a subscriber? Click here to sign up to the Change Notice Newsletter (A link will open in a new tab.)Hi friends,
Happy Fall! I took a little break from the newsletter to embrace the unhurried pace of August (difficult but important!) and then ramped up with a new client that I’m spotlighting called Stardust. Stardust is a period, hormone, and pregnancy tracking app that blends science, astronomy, and ancient wisdom to offer personalized insights into the magic and complexities of your menstrual cycle.
When I tell people I haven’t been this obsessed with a mobile app in a very, very long time—maybe ever, I get a mix of the following responses:
Why do we need another cycle tracking app?
Is there real science behind it?
Whoa, this is so cool!
I’ll address the above and much more (namely how to build and grow a consumer product and brand that feels like a piece of art) in an interview with Stardust’s CEO Rachel Moranis and their Head of Brand and Content, Isabel McWorter-Rosen who will tell us about the magic of Stardust. But first, some background and thoughts!
Co-founded by Moranis (a designer, artist, and entrepreneur) and Molly Young (a writer for the New York Times and former creative lead at Warby Parker), Stardust’s unique brand and user experience set it apart from other cycle tracking apps like Clue and Flo. Moranis’ background in art, design, and architecture combined with Young’s expertise in copywriting and storytelling, birthed (hehe) an app that looks beautiful and feels unusually culturally relevant. That’s why over one million monthly active users, and I, are hooked on learning more about our bodies. Built alongside an OBGYN, midwife, hormone coach, AI expert, astrologist, herbalist, and a doula to name a few, Stardust provides a holistic approach to women’s health and helps address a very real knowledge gap around menstruating bodies.
For those thinking this isn’t for you, here’s a fun fact: Flo, the leading menstrual tracking app, hit a $1 billion valuation two months ago after securing a $200 million investment. With 70 million monthly users, it’s a major moment for Flo and also for women’s health. Flo’s popularity, however, comes with some controversy—it’s founded by men, and many of its investors are male. This raises questions about how sensitive data is managed—especially in a post-Roe v. Wade world—and the type of research it's being used to support.
I also believe that having male founders in charge of a technology so deeply tied to the female and menstruating body experience can influence the overall design in ways that feel unnatural, unintuitive, and potentially harmful. For instance, Flo’s partner feature sends partners notifications like, 'Today your partner might feel...' with two options: 'High Sex Drive' or 'Everything is Fine.' Simplistic at best—reducing women to their reproductive functions, and borderline predatory at worst.
Personally, while my cycle is regular, I still wake up a few days before my period feeling like all the energy has evaporated from my body and that I’m trapped under a weighted blanket—and not in a good way. I cry more easily, whether I’m watching a manipulative Google commercial, reading the latest news headlines, or listening to an ABBA song that should otherwise make me happy. There’s also anxiety, bouts of depression, anger, bloating, and of course, the intense stomach cramps that feel like someone’s twisting a dull knife into my uterus.
In stark contrast, the week or so after my cycle, I feel like my blood has been replaced with Red Bull. Maybe a slight exaggeration, but the contrast between the weeks is significant. To get ahead of the mood swings and physical pain, I had experimented with other cycle tracking apps but nothing stuck.
A few months ago, a friend told me about Stardust, and as an astrology enthusiast, I was intrigued when I learned that the app incorporates astrology. Again, I understand if you want to stop reading at the mention of astrology, but for all my business-minded folks out there, the global astrology market size was valued at $12.8 billion in 2021 and is projected to reach $22.8 billion by 2031. A trend that shouldn’t be ignored.
Though the app has a witchy aura and a small astrological component (it tells you which house the moon is passing through and whether you have a high, low, or medium chance of having a Virgo baby if you’re trying to get pregnant), Stardust also merges modern medicine with time-honored practices like syncing menstrual cycles with lunar phases, seed cycling, and Ayurvedic traditions. It offers great educational content on everything from hormonal changes to recommended foods and exercises for different phases of your cycle.
Key features of the Stardust app
As you log symptoms, Stardust sends you push notifications that feel like they’re coming from a very funny and supportive best friend. On the first day of my period, when exhaustion hits and sensitivity is high, I’ll get something like, “Progesterone may cause sleepiness. Activate ‘low battery’ mode” or “Just try not to get into a fistfight today”. During other phases, I get notifications like, “You’re so drenched in estrogen it’s practically a state of spiritual advancement” or “Uterus getting thicc today”.
Notifications from the Stardust app
With playful features like “Sync with Friends” and entertaining yet educational descriptions of the four menstrual phases (I know I’m not the only person who didn’t know the term ‘luteal phase”), Stardust strikes a balance between entertainment and insight. Its ethos harks back to ancient menstrual rituals, celebrating female and menstruating bodies rather than shaming them.
Now, let’s get to our interview with Rachel and Isabel!
Leah: Rachel, can you tell me a bit about your background and how you decided to create Stardust?
Rachel: My background is in design and art. I studied art and architecture in college, and then I worked for a firm called Rockwell Group in New York, designing hotels and restaurants. I loved design, so I decided to study architecture. I got really lucky landing a job at a startup called Getaway, where I designed tiny houses. That’s when I realized I could never go back to working at a traditional architecture firm. It was just too fun building something from nothing and hanging out with friends all day. So, I decided to stay in the startup world.
In 2016, I joined The Wing, where Isabel was heading up their social media. I started working out of there every day, helping friends with their various startups, mostly doing digital design work. Stardust was just one of the projects I was tinkering with at the time, and it became clear that it had legs and was worth pushing forward. I did the design, I got my friend Molly to write the copy, and Ryan, who runs a dev shop, built the app. He could only give me his engineers when they weren’t working on client projects, so it took way longer than expected—what should have been six weeks ended up taking about a year. We officially launched it in late 2020 as a pandemic project. Isabel basically created the brand, managing the whole social media strategy before or right after the launch—honestly, I can’t remember exactly. We knew we needed to establish a presence, so I asked 30 friends to post about it on Instagram, and it grew through word of mouth. It was so cool. It scaled organically to a million users, and we eventually got some funding. Now, there’s a paid version of the app, and we’re running a full business.
Leah: Isabel, can you talk about Stardust’s brand and content and how it helps attract and retain customers?
Isabel: I think Stardust sits in a really interesting space in its category because we're so used to period-tracking apps being very clinical and rooted in science, which Stardust is, but we're not just that. We had a unique opportunity, because the app is built by the people we want to attract as users, to position ourselves as a peer and a friend—not as someone speaking from a moral or intellectual high ground.
Social media is obviously a powerful tool for brands, but I think a lot of brands get it wrong by fighting against what makes the platforms effective, rather than leaning into it. We see this with our competitors, where the content they post isn’t native to how people actually engage with social media. From the beginning, Stardust understood the platforms and approached our content strategy as an extension of the app, where humor and relatability are at the top of our priorities.
Social media is the front line for any company—it’s the widest part of the funnel. So for us, it’s about forging connections with people based on personality, rather than simply just delivering information or expertise.
I would be remiss not to mention having a CEO and founder who really gets it—someone with great taste and a really good sense of humor who lets that come through. I think that's pretty rare. It hasn’t been a point of contention here, as I imagine it might be at other companies, where brand or content teams suggest one thing, but the founder is married to their own vision of how they want to show up, even if it’s at odds with what’s actually effective.
Rachel: You reminded me, Isabel, that I forgot to mention this earlier—Stardust was created because there were no good cycle trackers out there. They were all super clinical, like medical products. But this isn’t something like cancer or heart disease; it’s everyday life. Yes, it’s health-related, but it’s so much more entwined with your mood and how you live day-to-day. It was fascinating that there was nothing fun or magical to interact with.
And, like many millennial women over the last five years, we all got really into astrology. Apps like Co–Star started popping up, but there was no app, and still isn’t, that connects the menstrual cycle to the moon. That feels like a validation of astrology—the idea that celestial bodies are governing our bodies. There’s this tangible, visible connection: we can see the moon, and we know there’s a mathematical link. It’s really cool to unearth all this folklore and indigenous wisdom from around the world and make it relatable, funny, and validating.
Isabel: I think by not taking ourselves too seriously, we actually end up doing more serious work. Inherent in that approach is a kind of reprogramming—helping remove shame or embarrassment and making it feel like an equalizer among our audience. When you look at competitors’ content, no one really wants to share a slideshow about BV on their story. But people want to share our content, and we benefit from that kind of endless echo.
Note: For those of you (like me) who don’t know, BV stands for Bacterial Vaginosis 🤠
Rachel: The whole brief for creating the voice was to make it sound like you're talking to your really funny best friend, right? And even though we’ve repeated some of them, I still get so much joy from the push notifications. A lot of the sharing on social media is people screenshotting their lock screen with the notifications because it feels so intimate—like getting an SMS from a friend. That’s still, to this day, the most effective part of the product and also a key sharing mechanism.
Leah: What are both of your favorite features of the app?
Rachel: My favorite feature is actually a forthcoming one that I can show you on our screen. You’ll be able to scroll down and see this blob that represents you in real-time. It’s designed to move based on how you slept, your cycle, and any symptoms you enter, like a living, breathing Tamagotchi avatar of you. We’re hoping it enhances the multiplayer experience, allowing you to check in on your friends and see how they’re doing.
Leah: Wow, I’m obsessed with that.
Isabel: In general, I’m really tickled by the design and the attention to detail in the app—the way things move is truly a piece of art. There are so many Easter eggs and things to discover if you’re looking for them. I’m a big fan of the Cyclopedia because, as someone who spends time on Wikipedia and Googles things out of curiosity, having a central place where all this information is presented in digestible language is fascinating to me. The hormone graph is also incredibly beautiful. Honestly, as someone who had no idea about their body until I started working for Stardust, I find it all so cool—who knew?
Leah: I love comparing the app to a piece of art. It’s true! We’re using these tools all the time, so why not make them look beautiful, exciting, and fun? How do you build inclusivity into the design, content, and product strategy of the app?
Rachel: I think we might be one of the only all-gender period trackers out there, though we're not 100% sure if Clue is doing the same. A few years ago, we made a significant effort to strip back all gendered language and remove a lot of gendered colors and aesthetics from the app. You’ll notice it’s rainbow-themed rather than just pink. Additionally, when we built our partner feature, we included options for same-sex partners and multiple partners, which was quite an engineering feat.
Isabel: In general, we try to avoid using gendered language, which is fairly easy because we’re talking to our users rather than about them in our content and social media. We focus on the emotional themes of the space we exist in rather than solely on biology, making our content resonate with a much larger cross-section of people since those themes are universal.
Leah: How does Stardust incorporate AI or how do you see that unfolding and you evolve your product?
Rachel: I think we’re seeing a lot of apps just throw in a chatbot, but we’ve decided to integrate AI in much more subtle and poetic ways. We’re still working on it, but we’re using AI to interpolate health data for a new feature. The goal is to make strides in women's health research. While we don’t have all the data yet, we’ve brought on our first machine learning engineer to explore how sleep changes across the cycle. We’re looking at whether specific symptoms are related to factors like weather, hormones, and any conditions users may have, and how these affect mood. We’ve also integrated a personality test, adding more facets of health and well-being. We’re not keeping this information to ourselves or selling it; instead, we’re delivering insights back to users to benefit them.
Leah: And I know you're integrating wearables in the next version of the app. I have a question about that later. But going back to AI, what are your thoughts on AI agents? Since the app has a “voice” that sounds like your funny friend, how do you feel about crossing that line between sending human-written push notifications that still feel like they're coming from a real person, and then moving into territory that feels too much like a real person?
Rachel: We've tried training our own GPT to sound like us, and it's the cringiest, weirdest thing you've ever heard—so bizarre and scary that nobody wants it. I don’t know what the secret is, but humor, by its very nature, involves connecting to things that don’t exist yet. That’s why you laugh; it's like, 'Oh my God, what a funny, creative idea!' When you create humor, you’re inventing something new, and AI can’t do that. It just regurgitates tried-and-true concepts, which isn’t interesting, novel, or funny. Plus, it lacks judgment. It actually cannot achieve what we’re trying to do. I don't know if we’re three years away from that, but part of me hopes it never gets there because we still need people.
Leah: A few months ago, I read this great book called Cycles, the Sacred and the Doomed. Inquiries in Female Health Technologies. One of the topics the author explores is the fine line between educating women and menstruating bodies about their health via technology and the risks of hyper-optimization. How do you balance users' desire for optimization with a more holistic approach that encourages slowing down and learning to trust their bodies, rather than following a tech-driven mindset?
Rachel: The product itself is like this slow storytelling experience—it's sort of about giving users one bit of information or education a day. We definitely don’t optimize for time spent in the app; we’ve never measured that. We take the opposite approach, really. We don't want users to be like Candy Crush-style or Instagram-style doom scrolling in our app. We kind of want them to check it and be done, like checking the weather—just checking in with themselves.
Isabel and I have had discussions about this with one of our advisors, especially in the spring. We tend to err on the side of validation—we're here for you as your friend—rather than pushing the message of 'get better' or 'get healthier' for longevity. We don’t really show a dashboard of data; instead, we focus on celebrating your body as art and magic, delivering funny, validating best friend texts. So, it’s all about that supportive, uplifting vibe.
Isabel: Yeah, I think that’s right. It’s like our tagline says: 'You’re a different person every day; we’re here for all of it.' We’re not coming in with the message that everything has to be perfect; we recognize that good and normal are subjective. If you’re experiencing something weird, trust me, millions of other people are too, so it really isn’t that strange. There’s an element of acceptance in that.
Especially considering how underfunded and under-researched menstrual health has been, the last thing we want to do is contribute to feelings of isolation or shame. It’s really a celebration of the magic of being alive in a body. Knowledge is power, and we want to equip people with the information they need to understand their bodies and make decisions for themselves, without imposing any weird beliefs about how they should be living their lives.
Leah: Okay, last question! How do you protect the data of your users? Do you think there’s a way for the data to be commonly owned by its users?
Rachel: So, we protect your data by anonymizing it. We have all this information, but we keep it separate and encrypted from your personally identifiable information, so we genuinely don’t know whose data is whose. That’s the best way to safeguard both the user and the company while still enabling cool features like syncing with your partner, connecting with friends, and tracking symptoms over time.
There’s a much safer version that would be localized only, but then we wouldn’t have any of those features. If you ever lost the app, got a new phone, or deleted it, all your data would vanish. There are period trackers out there that operate this way for those who prioritize safety first. For those users, I’d say just stick to paper tracking.
Now, we’ve also looked into users getting paid for choosing to share their data anonymously, but it’s honestly so unbelievably cheap. To sell any valuable amount of data, you need millions of pieces, and an individual user would be paid maybe two cents at most. It just doesn’t make sense.
The dream was for you to own your data and profit from it. We had another vision of allowing users to donate their data to science, partnering with places like the Mayo Clinic, but we needed to reach a critical mass that we’re not at yet. Plus, that data would have to be bundled and repackaged in a way that individual contributions would sort of get lost in the mix. So, while it’s a nice, poetic concept, practically, it’s not something we can implement just yet. But I would love to make it happen one day.
Leah: Thank you both so much!