Scaling Contraceptive App to 2M Users By Daring Not to Be Free

Something we got drilled into quite early by our investors was that we should never spend more on marketing than we get back right away from our customers. And also very early on, we dared not to be free. When we started this in 2013, every app was supposed to be free and just grow very quickly and then figure out how to monetise later. But we said: we're an app you use as a birth control method — we will charge for this. It makes sense.

And that way we managed to become profitable a few years back, and now we're also generating quite some profit this year. So that's exciting, because destiny has been in our own hands, not the investors' hands, which has helped us steer the business the way we want.

Yeah. And there's also the trust factor, which is very important for us. Why should you trust an app that's free as a contraceptive method? That's just weird — because how are you paying for it? By us sharing your data? No, that's not a good idea, right? So it's better for us to actually charge the customers — then the customers are actually our customers. But when we started 10 years ago, that was a very, very novel concept.

It was quite obvious to me in the beginning that you kind of needed a more mathematical background, like I have, to create this algorithm. But often when we talked to investors or healthcare professionals,

they'd say, "But you're not a medical doctor. How can you do this?" And I'd say, a medical doctor could not do what I'm doing. I always started to argue. But I realised quite quickly that it's not obvious to other people that it actually makes more sense for a physicist to create such an algorithm. Because the medicine behind it is well known and published — you know what's happening in the menstrual cycle, the hormones, how it changes the temperature. But to start Natural Cycles, I think one had to have more of the background I have.

It was actually a problem I'd had since I was quite young. I struggled to be on the pill as a teenager — I got a lot of mood changes. And I was thinking back then, if I just knew when I was ovulating, then I'd know when I'm fertile and I wouldn't have to solve this problem. Back then I went to the library and started reading up about how to track your cycle. It wasn't easy and fail-safe, and I gave up.

I had the contraceptive implant in my arm for many years — over 10 years I had three of them. But I also knew we wanted to have kids rather soon, so I was again facing the same issue: okay, I don't want to use hormonal contraception right now, so how can I avoid pregnancy until I'm ready?

And I realised the temperature changes. But of course I also realised this algorithm has to be made fail-safe — because women used to track their temperature by hand with very simple rules, and then it's not effective at all, because it doesn't take into account your previous cycles, or if you've just come off hormonal contraception. So I had to create an algorithm that also takes lifestyle into account — many things can affect temperature.

I started doing that with my own data. But of course all my female colleagues at CERN got very interested and started measuring and sharing their data — also the wives of the male colleagues. And I found online a big database of temperature data from women. So I started to optimise this algorithm on all the data I could get my hands on, both live and published. And I got very, very into creating this algorithm.

And I still am. I'm still working now with a great team of data scientists — many of them people I worked with at CERN during the Higgs discovery. My then-PhD students are now head of product. My colleague is our head of science and data. So we still work together on the algorithm. With more data, it can always be optimised further. But that is really my passion — the data and research part of it all.

I'd say the human body is much more complex than a car engine, and even more complex than weather patterns — although, if there's something else I like, it's definitely data on weather. If I weren't doing Natural Cycles, I'd probably do something with weather.

What makes it much more complex than, say, physics in some ways is that we all have a lot of different wills and interests, just because we're humans. If you picture particle physics, everything is a statistical probability and you can model it — not perfectly, but close to. But when it comes to measuring something in humans, things like what country you live in, what culture you're from, make a huge difference — much more difficult to model than a car engine, the weather, or particle physics.

It's a very good point. With wearables, for instance, we got the FDA clearance to integrate with the Oura Ring in — what was it — 2021 or 2022. But we'd been working on it since 2016, and at that point the wearables weren't good enough. The temperature sensors weren't there, weren't sensitive enough, and wouldn't work as well as measuring orally in the morning when you wake up. But technology improves with time, and at some point in 2021 we saw that the temperature from the Oura Ring was as good as measuring in the mouth in the morning.

Then a big part of it is on the algorithm side. That's why it has to be a rather complex, robust algorithm that takes a lot of things into account, learns from that person's unique cycle and temperature data and habits,

and doesn't assume she's like any other woman — because otherwise it wouldn't be as fail-safe.

But when it comes to contraceptive effectiveness — Natural Cycles is 93% effective with typical use and 98% with perfect use, meaning it's similarly effective to the pill — the difference between typical and perfect use is actually human behaviour. It's nothing to do with sensors or measurements. The only difference is: if we tell her today is a fertile day and you need to use protection, does she actually do that? So in the end, human psychology and intentions have a much bigger effect than any fine-tuning of the algorithm I can do.

It was very challenging, and many regulators did exactly what you said. We're one of the first apps cleared as a medical device at all — not just in women's health, but in health in general. When we started out — I think we launched in Sweden first, in 2014 — we asked the medical products agency: okay, are we a medical device or not? What type? And there was no answer.

So we just said, okay, let's launch this and see what happens. And we grew really, really quickly in the Swedish market — within a year we'd taken something like three to five percent market share. Then the medical products agency woke up and said, hang on a minute, maybe you should be regulated, maybe we should answer this question. They actually asked all the countries in the EU: this kind of app, what kind of medical device should it be, if any? And all countries came back with different answers.

But with their help — saying, okay, we have to fix this problem — we could go and do the clinical studies and get that regulatory approval. We got clearance in Europe in 2017,

and then FDA clearance in 2018.

I wish I could say that, since this is a product women want and need, that's all I needed to do. But it's not true. In the end, you also have to reach women somehow. Even though Natural Cycles has grown a lot and I'd say is a huge success — especially here in the US, which is our biggest market today — still many women, probably most women, have never heard of Natural Cycles. So the question is: how do we reach them? And how do we convince her to trust an app as a contraceptive method? That's not obvious. So it's important to reach her in a trustworthy way and explain, with very limited time and bandwidth, what Natural Cycles is and why she should trust it. It's not easy, so it requires marketing as well as just building an awesome product.

Not for our product. It might be different for others — a social media platform, the point is to interact with your friends, and it has that natural virality built in. Natural Cycles is something very private, something you use in your bedroom. We do get a lot of word of mouth — if we ask, "How did you hear about Natural Cycles?", hearing it from a friend is actually number one. But it's still not the majority — it's just the most common way. So we have to fuel that word of mouth, because it doesn't happen naturally like a platform where you add all your friends at sign-up.

When marketing people tell me, "We have to invest these millions of dollars and then in three or four months we'll see the results," I never buy that.

I'm a data person. If I don't see users coming in within an hour, they are not going to come in. And I'm always right. It has an exponential tail — of course some users will also come in next week from a campaign, but if they don't come in now, we're not going to wait around, spend more money, and think they'll come in next week. They won't. And that is never wrong.

Another thing — you mentioned CAC. Something we got drilled into early by our investors was that we should never spend more on marketing than we get back right away from our customers. And very early on, we dared not to be free. That way we managed to become profitable, and destiny has been in our own hands, not the investors' — which has helped us steer the business the way we want.

In the early days it was definitely regulation. I feel we've figured that out by now — we have clearances in Europe, the US, Canada, South Korea, Australia. We've done four FDA clearances by now, so it's not keeping me up at night anymore.

I do face very interesting challenges, though — it's always a little different. Every day I have to figure out something new. What I like the most is looking at the data. It can be all kinds of data: medical data we want to publish, but also, "Oh, why is this country not growing?" Trying to figure out why people in this market aren't as interested — is it the unit economics that doesn't work out? I love that data too.

So what keeps me up at night is probably sometimes when I get too focused on some corner of our data. It gets me so excited I start checking my data tool in the middle of the night — which I shouldn't, because it's somehow highly addictive.

So sometimes I wake up at midnight and I'm like, okay, it's a new day, I can look at all these metrics. But mainly it's exciting things that keep me up at night nowadays.

I do value gut feeling and instinct a lot too — mainly because I feel it's a compilation of all my years of staring at data. Put it all together, and that is my instinct. So I think gut feeling is very important, because in some cases measuring something would just take very long, cost a lot, or be very complicated to set up. Then you have to go with gut feeling — measure maybe something close to it, or draw conclusions and approximate a little from there. So I usually say 80% data,

20% gut feeling is a good mix.

You're definitely right, and unfortunately I also think more and more research is done just because people want to be able to say something. I get Instagram ads all the time — "You'll have no wrinkles if you use this" — and then you look at what's in it, and it's a lot of bullshit. But they've probably done some survey and some tests just to be able to say that. In the end, it comes down to the people, and whether they want to do the honest thing. What are they trying to achieve?

At Natural Cycles, we often get feedback from potential investors that we almost undersell ourselves, because we're a lot of scientists. I learned that the hard way — when I'd go out and pitch Natural Cycles, I wouldn't do it like other people. I'd almost undersell it and be very humble, because that's how we do things as scientists. We're like, "We can say this with 99% confidence, but we cannot really say it, because there's still that 1%." So I've personally learned to find a balance between the scientist and the entrepreneur and salesperson in me. But sometimes we also have to advocate internally

— like, okay, we probably have the best product of this in the world. This is what other people are claiming, this is what we're claiming. We shouldn't go all the way there, because we don't believe that's the right thing, but maybe we should go halfway.

I do think it's true. For instance, the forecast we make for the coming year — I'd like to make a forecast we can beat. But that's not what investors are used to seeing. This is what we think we can do — and then you put 30% on top and show it to an investor. But we actually show the one we also use internally and think we can beat, and often do beat — but then it's a downside for us, because they always take a haircut off it and assume that's the realistic one.

So I guess one has to learn to see: okay, who am I speaking to, what do they expect from me, and try to calibrate a little — but still being true to oneself.

It allows us to be in charge of our own destiny. I feel we have a responsibility to our users, and I sleep well at night because I know our users will keep having access to Natural Cycles — we won't die because we couldn't raise money in this market. But it also gives us the opportunity to do things that feel right, and take deals we think are right for Natural Cycles — and not have to take any deal just because we're running out of money. That makes quite a big difference, especially today.

That was at school, when I was a kid. Deep inside I was always a nerd, but I was also a pretty, blonde, popular girl. So I pretended to be stupid to be more likeable, I guess. I hope my daughter won't do the same, or won't have to. I think there's been a shift now — being a nerd is actually pretty cool.

But when I ask my daughter about it, she says no. She actually trashes me a lot, because I'm a nerd and I'm not cool. But of course I'm her mum, so I'll never be cool in her eyes.

I'd say the data is my superpower — being able to fetch my own data, almost any data, myself. If there's something I'm wondering about our customers — why aren't they using it to plan pregnancy in this market? — I can try

to dig it out on my own. And for instance, if we're talking to investors and they want to know something, I can always get it within a few minutes. That's a superpower, because if I had to ask someone to get it for me, or I didn't have it off the top of my head, I'd just be much slower at everything I do.

After we launched in the UK, we realised it's not just the customers — you also have to educate the healthcare professionals. We were lifted a lot by the press in the UK, but then also really torn down by them. What happened was that there were reports of unwanted pregnancies. To me it was like — of course, we've done a clinical study. This clinical study had 2,000 women; being as effective as the pill roughly means 7% per year get pregnant. For me as a scientist this is obvious. But what I didn't realise was that every pregnancy is also a sensational headline.

There was a journalist who wrote about her own pregnancy, for instance, and I'm like — but would you write it if you got pregnant on the pill? Probably not, because it's not a new startup. So that was something we had to learn and go through, which was really tough, because it felt like the whole world was against us.

We've since hired much better PR people who know how to deal with journalists. I'm not a PR expert myself, so it was a real learning curve — that one has to talk a certain way with journalists.

Horrible. I felt very, very misunderstood. Here I was, creating something I knew women wanted and needed, and there was absolutely nothing wrong with our product — it was always performing in line with expectations. So I felt truly misunderstood. But in some sense it also motivated me: I'm not going to die over this, I'll keep fighting, and I'll get my revenge one day. And it

did take almost three years to get back to where we were. But I'm very happy we did, and now it's quite long ago.

Yeah, I think about that a lot, actually. And I feel a little bit sorry for the self-driving cars — because people don't necessarily understand statistics, which I think is the reason behind this.

When it comes to contraception, today or tomorrow, there's never going to be one size fits all. Different women will want different things, also at different points in their lifetime. But I do think non-hormonal is a trend that will grow — because you hear so much, like women stopping using a certain shampoo because it impacts your hormones, but then they still take

a contraceptive pill, and they haven't realised that of course impacts your hormones much more than your shampoo. So I think we're seeing a shift as education increases around what we put in our bodies.

I hope in a decade or so we can have even smarter data. Wearables have gotten better, but I think the ultimate way is to measure hormones directly in your blood, continuously. I don't know if we'll get there in a decade, but I hope at least in my lifetime — because then we can become super smart about knowing what's going on inside. If we can measure all the different hormones inside the body continuously at all times — for me, as the passionate data person, that's of course the dream. So that's where I'm hoping we'll go. But I think hormonal contraception is also here to stay; it fills its purpose too.

It was a big deal for us, and we got quite a bit of questions from our users, especially around data sharing. But in the end, what happened is we actually got more users rather than fewer. Many women still today use a free period tracker as a contraceptive method — it's kind of like the calendar method, you guess roughly when you're fertile or not. It's not as precise, but you get a feeling for it, and it's free. But then many started realising: an app that's free is making money some other way — most probably through your data. And I think many of these women were also thinking, maybe I should have a more effective contraceptive method. So we saw quite a few users come to Natural Cycles — either because we're a medical device that is not free and would never share anyone's data, or because we're an effective contraceptive method.