Digital menstrual calendar - calculate your period and fertile days
Cycle apps are practical and therefore popular with many women. There is a wide range of apps available - for both Android and iOS. Their main purpose is to help you get to know your own body better. Your period is recorded in the digital calendar and can be monitored over any period of time. In addition, some apps provide users with tables, statistics and calculate the start of the next cycle. Some menstrual calendars work by measuring your body temperature after waking up, the so-called basal temperature, and observing cervical mucus. The cervix is the neck of the womb that forms the connection between the vagina and the inside of the uterus. Information on symptoms such as abdominal cramps, premenstrual syndrome (PMS) and mood swings can also be stored. Some use sensor technology to predict fertile days based on vital signs.
How reliable are ovulation calendars and cycle apps?
Since most cycle calculators calculate ovulation and the onset of the period purely mathematically, caution is advised. Some apps can be helpful if users want to monitor their cycle or plan a pregnancy. It becomes problematic if a period tracker is used solely for contraception. This is because certain life circumstances such as stress or chronic illnesses such as thyroid problems or taking medication can significantly delay the time of ovulation. Such forecast apps are therefore quite inaccurate - in other words, unreliable.
Stiftung Warentest: Menstrual calendars often inadequate
23 period apps were tested by Stiftung Warentest, most of which are available for free download. Only two of them received an overall rating of “good”. The weak point of the inadequate ovulation apps is their calculation system: the start of the period and ovulation are determined purely mathematically - often months in advance. Fertile days and the onset of menstruation cannot be reliably determined using average values. Every woman's personal life situation can influence the cycle. This means that not only does the cycle length fluctuate between 25 and 35 days, but the time of ovulation can also vary considerably. If couples rely on the app they use for contraception, this can lead to unwanted surprises. The result from Stiftung Warentest shows that using cycle apps for contraception can be risky, especially if they are not based on the symptothermal method.
“Good” apps rely on cervical mucus and basal temperature
What do the ovulation calculators classified as “good” do better? Instead of mathematical calculations, they use the symptothermal method. Entering the basal temperature and observing the cervical mucus are essential for this. Fertile days are indicated by clear and liquid mucus. If it becomes thick, it means the end of the fertile phase. This method requires a little practice at the beginning. But it is indispensable for a reliable evaluation.
Five cycle apps at a glance
Period diary or natural family planning (NFP) - which of the digital tools convince users and testers? Below are five apps that are particularly popular with users and have received positive reviews in tests.
Contraception app Lady Cycle
Whether it's contraception, wanting children or pregnancy - Lady Cycle made it to the top of the Stiftung Warentest. The app uses the symptothermal method to determine the fertile days. With each cycle, users enter information about their basal temperature or the quality of their cervical mucus in the application. Developments can be tracked over the long term.
The main functions of Lady Cycle are:
- Determination of the highly fertile days, increased chances of conception
- Observation and recording of symptoms during pregnancy
- Relationships between physical and mental state are observed
- Manual on NFP, tutorials and references are part of the app
The basic version is free, but is currently only available for Android. The premium version contains additional functions. These include personal statistics and analyses of the cycle as well as physical and mental well-being, priority for support requests and a clearly illustrated analysis of the cycles.
Clue menstrual calendar
The Clue menstrual app gives an overview of when women are likely to get their period. Additional data such as sleep duration, mood information and contraception can be stored in the application.
Clue has the following main functions:
- Period tracking and prediction of the next three periods
- Pill reminders
- Recording of basal temperature and prediction of fertile days
- Better understanding of the cycle: personalized analyses and averages of menstrual cycles
The basic version can be installed on the smartphone free of charge.
Ovulation calculator Flo
The menstruation app Flo offers a wide range of functions and received very good reviews in both the Apple App Store and the Google Play Store.
The main functions of Flo are:
- Health assistant through advice functions on skin and sleep
- Period and ovulation predictions based on artificial intelligence (AI)
- Daily health information
- Functions during and after pregnancy: images and articles from medical experts and recording of the baby's development
- Users can get support in the community if they have questions
This period app can also be downloaded for free.
Cycle calendar app Ovy
Ovy relies on a simple design and offers a good overview of the cycle length. A basal thermometer is also available for purchase. Measuring the basal temperature daily helps to determine the fertile days more precisely and supports pregnancy planning.
Ovy offers the following main functions:
- Plan pregnancy and track monthly cycle
- Evaluation using the symptothermal method
- Record important body signals, temperature and disruptive factors
- Users can share their data with their partner in their own cycle app
- Other products such as the Ovy Bluetooth basal thermometer make it easier to record waking temperature.
The Ovy app can be used free of charge on Android and iOS.
Ava Fertility fertility app and bracelet
The Ava Fertility, a wearable with an associated cycle app, uses sensor technology combined with scientific data to determine the fertile days. In principle, there is a chance of becoming pregnant on six days within a cycle. Using an algorithm, Ava evaluates important parameters such as skin temperature, resting pulse, blood flow, heart rate variability and respiratory rate and uses a clinically tested procedure to determine the five most fertile days.
The main functions of the Ava Fertility are:
- Tracking cycle development
- Recording five physiological signs of fertility
- The five most fertile days are determined to increase the chances of pregnancy
- Vital signs can be tracked during pregnancy
The Ava Fertility app is available free of charge on Android and iOS. However, it only works in combination with the Ava bracelet, which is not available free of charge.
Choosing the right cycle app
Users should ask themselves what the app should do for them in order to determine the functions they want. In addition to the apps mentioned in the article, there are many others that are very popular. These include Natural Cycles, Daysy and Femometer.
Cycle apps collect sensitive health data. Users should know how this data is stored and used, because some apps transmit user data without sufficient encryption. It is therefore advisable to prefer apps from providers who handle data transparently and store it in encrypted form.
In the best case, the user not only gets a helpful companion in everyday life, but also has the chance to get to know her body and cycle better and to actively monitor her own health.
The contents of this article reflect the current scientific status at the time of publication and were written to the best of our knowledge. Nevertheless, the article does not replace medical advice and diagnosis. If you have any questions, consult your general practitioner.
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