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Oura, the smart ring, is finally taking menstrual cycle data into account when assigning readiness scores—a feature whose absence has baffled users for years. The ring’s app was notorious for assigning lower-than-expected scores during the luteal phase of users’ cycles, but that is changing thanks to an update to the Readiness score algorithm that Oura announced this week.
If you don’t have a menstrual cycle, or if you have one but don’t track it, you probably won’t notice anything different about your Readiness scores. But this update is a big deal for anyone who uses Cycle Insights, the feature of the Oura app that uses temperature data to keep track of ovulation, menstruation, fertile window, and follicular and luteal phases.
Why many users had incorrect readiness scores
To explain why this was an issue, I’m going to zoom out and give a quick biology lesson. The monthly cycle that’s sometimes called a menstrual cycle isn’t just about menstruation, i.e., the bleeding that lasts a week or less. Instead, the cycle is a phenomenon that lasts all month, with distinct phases in the first and second halves of the month.
To be clear, this cycle doesn’t happen in everyone. It’s specifically a phenomenon that occurs in people who have a regular period and are not taking hormonal birth control. If you fall into this category, you can use the Cycle Insights feature of the Oura app to track when you are in the first half of your cycle (the follicular phase) versus the second half (the luteal phase).
(An important aside: Every time I write about menstruation or hormonal cycles, I get someone writing in to tell me that “women” and “people who menstruate” are synonyms. Let’s just take a minute to discuss the fact that they are not. Not only can we acknowledge the existence of trans folks, non-binary people, and a strange species of human known as “girls,” it’s worth remembering that a significant percentage of women do not have a cycle! This includes women who are past menopause, and women who use hormonal birth control.)
When your cycle starts on day one of your period, you’re in what’s called the follicular phase, as an ovarian follicle (which will produce an egg cell) develops over the course of about two weeks. Midway through the month—day 14 in a textbook cycle—that follicle releases the egg, ending the follicular phase. The releasing of the egg is called ovulation.
At this point, the body’s temperature ticks up by about half a degree. It will stay at this slightly elevated temperature for the rest of the cycle, and the Oura ring can detect the change in temperature. The empty follicle stays behind in the ovary, secreting hormones, and becomes the corpus luteum, Latin for “yellow thing.” (Scientists are so creative.) In its honor, the second half of the cycle is called the luteal phase.
Temperature isn’t the only difference between the follicular and luteal phases; all kinds of hormonal and biological phenomena are happening throughout the month, some of which have catchy names like “period flu,” but that’s a discussion for another time.
What’s changing in the Oura algorithm
As Oura points out in their announcement about the change, the luteal phase tends to have a few detectable differences from the follicular phase (from the ring’s point of view):
Skin temperature increases
Respiratory rate increases
Resting heart rate increases
Heart rate variability (HRV) decreases
All of these are things that, if they weren’t associated with the menstrual cycle, would indicate that a person is under stress or maybe getting sick. And so the algorithm (at least sometimes) processes this data as dings to your Readiness. Forums that discuss the Oura ring are full of threads with titles like “PSA to Oura: luteal phase is not a sickness” and “Anyone else get terrible readiness during luteal phase?” (according to the comments: yes).
With that in mind, Oura is finally taking your cycle phase into account when calculating Readiness scores. They predict that 35% of users who track a menstrual cycle will no longer get “disproportionately negative” readiness scores in the luteal phase. They expect that scores will be four to five points higher for those people, and that there will be 81% fewer days with too-low scores.
How to get the updated readiness scores
To benefit from the new algorithm, you’ll need to be using the Cycle Insights feature. This requires you to input the dates that your periods start, and it detects temperature changes to determine when you are in the luteal phase.
To turn on Cycle Insights, tap the menu icon in the app, then Settings, and then Women’s Health. There is a switch to turn on Cycle Insights, and below that you can enter some background information: whether you use hormonal contraception, how long your typical cycle lasts.
So, yes, this means that the app will need to keep track of when you have your period and when you’re ovulating. If that makes you uncomfortable in the current political climate, I don’t blame you—but you’ll have to decide whether it’s worth it to get that slightly more accurate data. Oura has a blog post on their approach to reproductive data privacy, noting that they are subject to GDPR regulations (since they are based in Finland) and that they plan to fight any requests for data from legal authorities. The support page for Cycle Insights includes instructions for deleting your cycle data from the app, which you can do at any time.
