​Research shows this pulse tracking wearable can help you to get pregnant

We speak to 'Fitbit for fertility' Ava about the link between pulse rate and fertility
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From detailed calendars to basal body thermometers, tracking your cycle to work out the best time to conceive is far from new. But with the help of smarter devices and fertility tracking wearables, many are getting a better, simpler and more accurate grasp on when they're most likely to get pregnant - and most likely to not get pregnant - than ever before. Today self-proclaimed 'Fitbit for fertility' Ava tells us it can make fertility tracking even more precise by measuring a different data point - your pulse.

The state of fertility tracking tech

Many connected self devices and fertility tracking wearables collect data about temperature, which has been used as a marker for fertility for a long time. Wink claims to take your temperature four times faster than a standard thermometer and feeds data into the Kindara app. The Yono in-ear thermometer takes your temperature from within your ear as soon as you wake up. Daysy is meant to be super accurate and works alongside an app to give you a precise idea about when your fertile window will be. Then there's also tracking apps like Glow and Clue, which can sync up with the wearables above or be used on their own as advanced cycle tracking tools that predict when you're most likely to be ovulating based on data from past months.

And that's just the beginning. But an influx of tech designed with fertility in mind has been long-needed. For many, fertility tracking has historically relied on confusing data, second guessing and lots of trips to the GP or a specialist - especially if you had an irregular cycle or pre-existing medical conditions. It was calling out for a change.

​Research shows this pulse tracking wearable can help you to get pregnant

Ava wants to help women track their fertility in a different way. So far it's one of only a few devices on the market that tracks nine different physiological parameters in order to better understand your cycle. (It's similar to Tempdrop, but tracks more data points). Furthermore, the insights are fed back to users in real-time rather than after the fact, so unlike a lot of temperature-based methods, you know when you're most fertile, not when you were.

The power is in your pulse

Ava currently uses a bevy of sensors to collect data about your physiological stress levels, sleep quality and quantity, skin temperature, weight and pulse rate. And it's this last one that's due to make waves because the Ava team has just announced its clinical trial of 91 women, which looks specifically at the importance of pulse rate in detecting fertility, has been published in the peer-reviewed journal Scientific Reports.

So far Ava is proving successful. Lea von Bidder, the company's CEO, told us that the $199 tech bracelet has currently helped around 75 women conceive since it was launched last August, with the first 'Ava baby' due this summer. Although it's still early days for the device, it's already proven to work for some women, at least anecdotally. But now the trials have been published in Scientific Reports, Ava's claims have garnered more significant backing.

"Ava has already been using the learnings from the clinical study in the algorithm, so the publication of the study doesn't change anything about the product," Lea von Bidder said. "But it's a milestone in terms of being published in a peer reviewed journal. This recent paper is the first published results from our clinical study. It shows that resting pulse rate supports the identification of the beginning of the fertile window."

Using pulse rate to find out more about fertility isn't new, but it's the way Ava combines these findings with other data points that is. "At Ava, we are using resting pulse rate as part of a multi-parameter approach to identify the fertile window," she said. "Specifically, we are able to identify an average of five fertile days per cycle using pulse rate and other physiological parameter data."

What can pulse rate help us understand?

It's clear that tracking your pulse is important, but we wanted to better understand why. One of the main reasons is that we're all so different. For some women, simply tracking your cycle month on month can paint a really accurate picture of when you're most fertile. You track your cycle each month and a few months later everything is like clockwork and you're more likely to conceive. It sounds too good to be true because often it is - there are so many different factors to consider.

We spoke to the Peter Stein, the co-founder and vice president of Research and Development at Ava. "The study demonstrates the robustness of pulse rate correlation with the menstrual phase given a broad spectrum of menstrual cycle duration," Stein explained. "And under a range of different daily activities such as the consumption of coffee, alcohol, and large meals before sleep as well as other activities such as sports, showers, and intercourse or on the background of different BMIs."

​Research shows this pulse tracking wearable can help you to get pregnant

It's not just environmental factors that can make one person differ from another, but irregular cycles. Here pulse rate becomes invaluable when it comes to joining the dots when cycles aren't what's considered 'regular.'

Stein explained: "Novel in our study is the demonstration that the association between the elevated pulse rate of the ovulatory phase compared to menstrual phase is observable even in irregular cycle lengths. Despite the participants reporting regular cycle length during recruitment (cycles between 24 – 35 days), 56 of the cycles (15 %) collected during the study were below or above that range. We analysed these 56 irregular cycles separately to assess whether the same associations could be observed."

Keen to dig deeper into the study of pulse rate, we asked Stein whether pulse only changes when women are fertile or whether it's a constant up and down throughout the month.

"We observed the same significant increase of pulse rate between the fertile window and the menstrual phase, however the magnitude of the increase was marginally smaller," he said. "The increase of pulse rate between the mid-luteal phase and the menstrual phase was also minimally reduced. However, this difference could be attributable to the smaller number of irregular cycles at hand."

So there's no obvious rule here - pulse rate changes, the changes are just marginally more significant during the fertile window. Therefore, it's all about using tech to most accurately gather the data, which is what sets this research apart from anything that's come before it.

Why a wearable?

Professor. Dr. Brigitte Leeners, a renowned fertility and women's reproductive health expert who led the study at the University Hospital of Zurich, said, of the headline findings: "In our research, we found that resting pulse rate usually is lowest during menstruation but rises significantly five days before ovulation and again after ovulation. Ava is the first technology that uses temperature, resting pulse rate, and other parameters, including heart rate variability, sleep and bioimpedance, to provide a convenient and accurate at-home method to identify the beginning of the fertile window."

Explaining the importance of a wearable device, Lea von Bidder expanded on this: "Previous studies have identified the correlation of menstrual cycle phase to pulse rate, but these have never used a wearable device of any kind. They required women to come into a lab and take their pulse rate by hand."

It's not just Ava's accurate sensors that paint a more detailed picture of fertility, or the fact it removes some human error, but the fact you only need to wear it at night: "We measure pulse rate continuously during sleep. Sleep is considered a more favourable condition to measure the influence of sex hormones on cardiac activity, as it minimises the influence of external conditions that can affect the heart rate."

From a personal point of view, the fact Ava tracks everything at night isn't just appealing because it's more accurate, it'd be a lot more practical, less annoying and more likely that I'd wear it.

Real time body data

​Research shows this pulse tracking wearable can help you to get pregnant

Since lots of fertility tracking tech has been released recently, we wanted to ask why Lea von Bidder feels Ava offers up something new beyond the accuracy of the sensors. And it's really all to do with timing. Firstly, whereas period tracking apps rely on average cycle length, Lea von Bidder explained that Ava works "to identify the fertile window in real time."

Similarly, basal body temperature, or BBT, is a method that's been around for a long time and requires women to take their temperature to work out their fertile period. "This method can only identify after ovulation occurs, when it is already too late to conceive that cycle," she explained. "Ava, in contrast, identifies the beginning of the fertile window and it does not require the user to remember to wake up every day to record her temperature."

And finally, Ovulation Predictor Kits (OPKs) are urine tests that the user must take for multiple days (and sometimes multiple times per day) throughout her cycle in order to detect the rise in luteinizing hormone that occurs a day or two before ovulation. "These are annoying to use for obvious reasons," Lea von Bidder told us. "And only provide a day or two of warning before ovulation."

To many who haven't been through the process of trying to conceive and being constantly disappointed, the current options may already seem accurate enough. But there's something particularly empowering about not just understanding your body, but understanding it in real time rather than after the fact. Sure these differences may sound subtle - why not just wait till next month? - but for those desperate to conceive, this kind of knowledge could be invaluable and, for many with irregular cycles who have had to rely on numerous GP visits and constant tracking, possibly ground-breaking.

The future of fertility tracking

Ava isn't the only company innovating in this space. Natural Cycles made mainstream headlines late last year for claiming its fertility tracking algorithm could be just as accurate as some of the most popular forms of contraception when it comes to preventing people from getting pregnant. For many, current contraceptive methods often feel limited, and the options that are available come with lots of hormonal, emotional and physical side effects. We're interested in seeing how companies can use fertility data to prevent pregnancy as much as it can aid it, and the team at Ava agrees.

"Contraception is something we are highly interested to pursue in the future," Lea von Bidder told us. "It is our strong vision to support women in all life stages with the data and insights they need." Many of the physiological parameters Ava tracks have been known to directly correlate with fertility and have been successfully tracked by woman and medical professionals for years. What we're most excited about in the future is how the tech and medical communities can work together to find ways that metrics - like pulse rate - presented with regular people in mind can help people better understand their bodies in real-time.

How we test

Becca Caddy


Becca has been writing about technology for nearly ten years. In that time she’s covered topics from robotics and virtual reality to simulated universe theory and brain-computer interfaces for a wide range of titles, including TechRadar, New Scientist, Wired UK, OneZero by Medium, Stuff, T3, Metro and many more.

She’s passionate about helping people wade through tech jargon to find useful products they’ll actually use – with a focus on health and wellbeing.

Becca is also interested in how scientific developments and technological advances will impact us all in the near future. Many of her features ask big questions about what’s in store for wearable technology, especially the potential of virtual reality and artificial intelligence.

She spends a lot of time interviewing researchers and academics to explore the ethical implications of a world increasingly filled with tech. She’s a big fan of science-fiction, has just traded in her boxing gloves for weight-lifting gloves and spends way too much time in virtual reality – current favourites include painting in TiltBrush and whizzing through space in No Man’s Sky.

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