Digital menstruation calendars – Calculating periods and fertile windows
Apps are a practical (and therefore popular) way to track the menstrual cycle. The number of cycle-tracking apps currently available for Android or iOS devices is almost overwhelming. However, they share the same primary aim: to help users get to know their bodies better.
The menstrual cycle is recorded in a digital calendar, where it can be easily monitored over an extended period of time. Some apps also include tables and statistics and can predict the start of the next cycle. In addition, some menstruation calendars incorporate measurement of the waking (basal) body temperature and observation of cervical secretions. Symptoms such as abdominal cramps, premenstrual syndrome (PMS), and mood changes can also be recorded. Other solutions use sensor technology to predict fertile days on the basis of vital signs .
How reliable are ovulation calendars and cycle-tracking apps?
Because most cycle calculators calculate ovulation and the onset of menstruation using mathematical methods, users should exercise caution. These methods are perfectly adequate for those who simply want to monitor their cycle. Some may also be suitable for people who wish to become pregnant. However, problems can arise if users rely solely on a period tracker for birth control. Stress, medications, and other factors can all affect the timing of ovulation.
German consumer organization Stiftung Warentest rates many digital menstruation calendars as “unsatisfactory”
Results obtained by the Stiftung Warentest show considerable room for improvement when it comes to the accuracy of cycle-tracking apps . The German consumer organization tested 23 period apps, most of which are available to download free of charge. Only two of these received an overall rating of “good.” The major weak point of ovulation apps rated as “unsatisfactory” is their calculation system, which calculates ovulation and the onset of menstruation using purely mathematical means, often months in advance.
However, average values can predict fertile days and the onset of menstruation in very few cases. Personal life factors can also affect the menstrual cycle. Not only can the length of the cycle fluctuate between 25 and 35 days, but the time of ovulation can also vary considerably. Couples who rely exclusively on an app for birth control may be in for a life-changing surprise .
Apps rated as “good” rely on basal body temperature and cervical secretions
So, what’s different about the ovulation calculators with a “good” rating? Instead of mathematical calculations, these apps use the symptothermal method, which relies on measurement of the basal body temperature and observation of the cervical secretions.
The cervical mucus is thin and clear on fertile days, becoming more viscous at the end of the fertile window. Although this method certainly takes some practice at the start, it is indispensable for a reliable evaluation of the menstrual cycle.
An overview of five cycle-tracking apps
Menstruation diaries or natural family planning (NFP): which digital tools were a hit with users and testers? Read on to learn more about five apps that were especially popular with users and rated highly in tests.
Lady Cycle birth control app
Whether used for birth control, to support conception, or to monitor pregnancy, Lady Cycle topped the list at Stiftung Warentest Deutschland. The app uses the symptothermal method to determine the fertile days in the menstrual cycle. Users can systematically record their basal body temperature and the consistency of the cervical mucus in the app for each cycle so that changes can be tracked over the long term.
Main features of Lady Cycle:
- Determination of highly fertile days in the cycle to maximize the chances of conception
- Monitoring and documentation of symptoms during pregnancy
- Observation of interrelationships between the body and mind
- NFP manual, tutorials, and references included in the app
The basic version is available for free, but is only available for Android devices. Additional features in the premium version include personal statistics and analyses of cycle characteristics as well as physical and psychological well-being, priority support, and a detailed menstrual cycle chart .
Clue menstrual calendar
The Clue menstrual app lets users know when their next period is due. It also allows them to log additional information on sleep duration, moods, and contraception.
Main features of Clue:
- Period tracker and predictions for the next three periods
- Pill reminders
- Logging of basal body temperature and prediction of fertile windows
- Helps users make sense of their menstrual cycles with personalized analyses and calculation of average values
The basic version can be installed free of charge on a smartphone .
Flo ovulation calculator
The Flo menstrual app has a wide variety of features and attracts very good ratings in the Apple App Store and Google Play Store.
Main features of Flo:
- Health assistant with advice on skin issues and sleep
- AI (artificial intelligence)-based period and ovulation predictions
- Daily health insights
- Useful pregnancy and post-pregnancy features, including a baby development tracker and visuals and articles developed by medical experts
- Users can ask questions and get support from the community
This app is also available for download free of charge .
Ovy cycle calendar app
Ovy focuses on simple design and a clear overview of cycle length. The Ovy ovulation thermometer is available for purchase as a complementary product. Daily measurement of the basal body temperature helps to determine fertile days more precisely, helping users who are trying to become pregnant .
Main functions of Ovy:
- Pregnancy planning mode and period tracking
- Evaluation based on the symptothermal method
- Documentation of key body signals, temperature, and interference factors
- Option to share cycle details with a partner in the Ovy Partner app
- Additional products such as the Ovy Bluetooth thermometer to make it easier to log the waking temperature
The Ovy app can be used free of charge on Android and iOS devices.
Ava fertility bracelet
The Ava Fertility Tracker 2.0 is a wearable device linked to a cycle-tracking app that uses sensor technology combined with scientific data to detect the fertile window in real time. There are six days in a cycle on which it is possible to conceive. Ava has been clinically proven to recognize five of these using an algorithm that evaluates key parameters such as skin temperature, resting pulse rate, perfusion, heart rate variability ratio, and breathing rate.
Main features of Ava Fertility Tracker 2.0:
- Cycle tracking
- Tracking of five physiological fertility indicators
- Detection of five out of six fertile days to maximize the chances of conception
- Monitoring of vital signs during pregnancy
The Ava app is available free of charge on Android and iOS devices. However, it only works in conjunction with the Ava Fertility Tracker 2.0, which must be purchased .
Choosing the right cycle-tracking app
Users should first identify long-term goals before choosing an app to make sure they get the features they need. It’s also a good idea to check the app provider’s policies on data protection and privacy to ensure they meet all expectations. For users who have a clear goal in mind and are satisfied with data protection measures, a cycle-tracking app can provide useful support in everyday life. It can be an opportunity to better understand one’s own body, health, and cycle in the long term .
 https://www.test.de/Zyklus-Apps-im-Test-5254377-0/ [German]