We may earn a commission from links on this page.Oura, the smart ring, is finally taking menstrual cycle data into account when assigning readiness scoresa feature whose absence has baffled users for years. The rings 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 dont have a menstrual cycle, or if you have one but dont track it, you probably wont 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 scoresTo explain why this was an issue, Im going to zoom out and give a quick biology lesson. The monthly cycle thats sometimes called a menstrual cycle isnt 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 doesnt happen in everyone. Its 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. Lets 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, its 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, youre in whats 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 monthday 14 in a textbook cyclethat follicle releases the egg, ending the follicular phase. The releasing of the egg is called ovulation.At this point, the bodys 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 isnt 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 thats a discussion for another time.Whats changing in the Oura algorithmAs 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 rings point of view):Skin temperature increasesRespiratory rate increasesResting heart rate increasesHeart rate variability (HRV) decreasesAll of these are things that, if they werent 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 scoresTo benefit from the new algorithm, youll 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 Womens 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 youre ovulating. If that makes you uncomfortable in the current political climate, I dont blame youbut youll have to decide whether its 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.