Can't revise menstruation data from >3 days prior Your product doesn't allow you to go back to revise menstruation data if it has been 3 days since the entry. This makes it extremely frustrating if you've already logged multiple months of data, and now have to do a factory reset in order for Daysy to accurately track your cycle. I have contacted Daysy about this issue, and have not been given any way to fix this issue without reseting the device and starting its tracking from day 1. I haven't found any cases online of other customers who have been able to resolve this issue either.

Definitely not worth your money This has to be my biggest Amazon purchase regret and I wish I could return it after 4 months of trying. It is so hard to use, hard to remember how to use, the app sucks, and this technology is not nearly as smart as it leads you to believe. You can’t track your period start days unless you remembered to take your temperature that morning and you can’t go back and update information from over 3 previous days so if you forgot to take it your temperature you’re screwed. You have to manually sync the Daysy to the app and the app to the Daysy- this is fairly straightforward but not something you’d expect from a €300 device. The app feels outdated and pales in comparison to competing apps like Flo. I sincerely do not know how this has 5 star reviews on every platform. If it were €20, it’s totally worth the money. Maybeeee €100. But €300 is ridiculous for how cheap it feels, how outdated it is, and how complicated it is. I seriously doubt this was even made by women for women.

When Daysy did an app update they… When Daysy did an app update they didn’t notify any of their customers that they would no longer be able to edit their mensuration period. This meant for me that my cycle was thrown off which took months to get back on track. I have seen a lot of articles that state their research is not accurate and I have lost my trust in them.

Works extremely well Daysy helps me monitor my fertility for preventing pregnancy, and it has worked perfectly so far. The app is great and I have had no issues with the device or the app. I love being able to download the charts and analyze my biology. Once I got a higher number of red and yellow days, so I reached out to customer support. Within one business day someone responded and provided an in depth analysis and advice.

Careful If you are thinking in investing in this device you need to remember one important thing: Daysy is, in the end, just a fertility tracking method. It DOESN'T protect you from unwanted pregnancy (even though the company tries to sell it as if it would, in a very subtle way, and of course without taking any accountability). I got unwanted pregnant with it 2 times, now we switched on using condoms only religiously. I know from 2 other women in my friends circle who had the same "accident". So, please be careful. I still keep the device tho, in the case i will want a baby in the future, because it gives you a better overview of the best fertile days. Oh, one more thing: Beware of the paid reviews (that are in high amount on Trustpilot as well) ;)