DEFRITEN
 
 
 Documenting body signs with the symptothermal method. 
 
 
 
Symptothermal method
With the symptothermal method, two ovulation signs are analysed together to determine your fertile and infertile days in the cycle. It combines the analysis of your waking temperature with the consistency of the cervical mucus or the cervix.
 
 
 
 
 
 
 
 
 
 
 
 
 
 Last updated on 25.07.2026 
 
 
Did you know that the symptothermal method is based on the temperature method? In short, one further symptom is simply added to increase the accuracy of the calculation.
 
Convinced by the symptothermal method? Find out everything you need for its application & which digital helpers are available.
  
What is the symptothermal method?
 
The symptothermal method is one of the methods of natural family planning (NFP). In everyday language, it is often equated with 'the NFP method'. This is probably because the symptothermal method is the most reliable of these methods. In fact, there are also the basal body temperature method, the calendar method and the cervical mucus method (Billings method).
 
  Banner: predicting your mood  
 
The symptothermal method is designed to identify the day of ovulation and thus the fertile days in the menstrual cycle. This knowledge can be used specifically for getting pregnant, for natural cycle observation, or for hormone-free contraception. The method combines two reliable ovulation signs: usually the basal body temperature method combined with observation of the cervical mucus.
 
How does the symptothermal method work?
 
And this is how the symptothermal method works in practice:
 
     
  1. Measuring the basal body temperature: the most important fertility sign for this method is the basal body temperature, the core body temperature right after waking up.  Measuring the basal body temperature requires a so-called basal thermometer. The waking temperature rises by at least 0.2 degrees Celsius after ovulation. If you enter the readings in a cycle sheet and connect them, you get a cycle curve, as shown in the picture.
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  2. Recording the consistency of the cervical mucus or cervix: the consistency of the cervical mucus is usually used as the second fertility sign. Some women find mucus observation difficult because they cannot detect any mucus or any change. Observing the cervix can replace observing the cervical mucus.
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  Analysing the symptothermal method  
Entering body symptoms in a cycle sheet
 
Second ovulation sign = cervical mucus
 
The cervical mucus changes from the beginning to the end of the cycle. While it appears in smaller amounts and is thicker during the infertile period, the mucus becomes more fluid and stretchier during the conception-ready period. These changes are observed and analysed in the Billings mucus method.
 
Second sign = the cervix
 
You feel the cervix and its consistency. The results of your self-examination of the cervix allow conclusions about your fertility.
 
 What makes the symptothermal method so reliable?
 
The symptothermal method offers a decisive advantage: it combines the sign that ovulation has already taken place (= rising basal body temperature) with a sign that ovulation is about to take place (= consistency of the cervical mucus or cervix). Our chart shows you an example of this. S+H shows you the cervical mucus peak, which indicates the upcoming ovulation, while the temperature rise is only recorded after ovulation.
 
  Diagram of cervical mucus, cervix and basal body temperature  
Symptothermal method: basal body temperature, consistency of the cervical mucus or cervix as fertility signs
 
If intercourse actually only takes place on the reliably determined infertile days, this system is very safe. On the fertile days around ovulation, you should additionally use hormone-free contraception, for example a barrier method, if you do not want to get pregnant. When used according to the rules, the symptothermal method is considered the safest and most reliable natural contraceptive method.
 
The method also has no side effects and offers the advantage of being able to give clues about possible cycle disorders: if you know your cycle, you quickly notice when something is wrong. The symptothermal method can, for example, give clues about an irregular cycle or other cycle irregularities such as a corpus luteum insufficiency.
 
 How do I use the symptothermal method?
 
You can apply the method either manually or with the help of a cycle computer or a cycle app. We show you both options here.
 
Manual application: what do you need?
 
     
  • A cycle sheet or cycle diary for recording your cycle curve
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  • basal thermometer, digital or analogue, with two decimal places, for measuring the basal body temperature
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  • A pen for entering your temperature readings and other ovulation signs in your cycle sheet
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  • Possibly an alarm clock, so you can measure at the same time of day whenever possible, as this increases the accuracy of the measurement.4
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  • Mastery of the rules of the symptothermal method, so you can derive the correct fertility status from the cycle data.
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Tools: symptothermal cycle computers & cycle apps
 
Manually analysing the symptothermal method requires experience, time and a precise eye. The tools from cyclotest can support you and take over a large chunk of the 'work'.
 
 
 
 
    cyclotest mySense basal thermometer next to a smartphone with the cyclotest app: 36.87 °C, status 'highly fertile', 'Lifetime'   
 
 
  cyclotest mySense Lifetime  
 
 
 
 
 
 
 
 
 
   
 
 
  
 
  
 
 
 
 
     
  • cyclotest mySense and cyclotest myWay both work according to the symptothermal method.
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  • Both products analyse two ovulation symptoms: either basal body temperature + cervical mucus peak, or basal body temperature + ovulation test results.
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  • Both products are suitable when trying to conceive and for natural cycle tracking. cyclotest myWay is additionally approved for contraception.
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  • The analysis happens automatically and makes application easier.
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  • The method is very reliable when used correctly.
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  • Observations of the cervix can also be recorded, but not analysed.
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  The screen shows which entries can be made in the cyclotest mySense app.  
cyclotest mySense: input options
 
Rules of the symptothermal method
 
The infertile days after ovulation are easier to determine than those before. They can be established with a double check through the temperature rise and the change in cervical mucus quality. To be able to assume an infertile phase at the beginning of the cycle before the day of ovulation, there must have been a high temperature phase in the previous menstrual cycle.
 
We briefly explain the most important rules for using the symptothermal method:
 
     
  • Minus-8 rule: the so-called minus-8 rule states that the 7 days before the first elevated temperature reading must be assumed to be conception-ready. The 8th day before the rise would therefore be the last infertile day of the cycle. This rule may only be applied once the first higher temperature reading has been determined from at least 12 cycles. If the consistency of the mucus indicates fertility earlier, the fertile period already begins at that point.
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  • 5-day rule: if 12 evaluations are not yet available, the 5-day rule is applied. In the first cycle in which you use the symptothermal method, however, you should assume fertility from day one, as some women must expect larger fluctuations. From the 2nd cycle onwards, the first 5 days of the cycle are considered infertile, as long as the mucus does not already indicate 'conception-ready' earlier. If a temperature rise occurred on the 12th day of the cycle or earlier during the first 12 cycles, the fertile period must also be assumed earlier and the minus-8 rule applies.
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  • Infertile days with cervix examination: if you replace the examination of the cervical mucus with that of the cervix, the following applies: if after your period it remains unchanged, you can assume infertility. Unless the 5-day rule or the minus-8 rule already points to the fertile days.
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  • Highly fertile days with cervix examination: if the cervix is high, soft and wide open, highly fertile days can be assumed. A hard, closed cervix must be observed on three consecutive days in order, in conjunction with the temperature, to assume an infertile period after the time of ovulation. In terms of reliability, combining it with temperature measurement is equivalent to combining temperature measurement and mucus observation.2
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Areas of application of the symptothermal method
 
Many couples use this method to give their wish for a child a targeted boost. Other couples use it for natural contraception.
 
Trying to conceive: increase your chances with sex on the right days
 
If you are longing for a pregnancy, this method can be very helpful. Through fertility awareness, you can quickly determine whether and in what time frame your ovulation occurs. The highly fertile days in the menstrual cycle are also determined, on which fertilisation of the egg is most likely and it is possible to get pregnant quickly.
 
  Banner trying to conceive: sex on the right days  
 
 
 
Possible cycle irregularities, such as a corpus luteum insufficiency, which may indicate a gynaecological condition and could be an obstacle to fulfilling the wish for a child, can also be uncovered.
 
Natural contraception with the symptothermal method
 
Thanks to the double check of two symptoms, the symptothermal method is considered the safest contraceptive protection without hormonal substances.4 Unprotected intercourse may only take place on the infertile days. During the fertile days around ovulation, hormone-free contraceptives must additionally be used, or sex must be avoided. Barrier methods such as a diaphragm or condom are suitable for this.
 
But beware: a diaphragm is often used with a chemical agent, which can alter the cervical mucus.
 
 
Precise cycle observation
 
Of course, more awareness of your own body processes can also come from keeping a cycle calendar. But the symptothermal method expands the overall picture enormously, as connections and irregularities can be recognised better:
 
     
  • Did ovulation even take place this cycle?
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  • Was my second cycle half shortened?
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  • Am I late because my ovulation happened much later than usual this time?
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  • Is my mood perhaps low because my period is about to start?
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FAQ
 
 
 
  
 
 
If you use the symptothermal method according to the rules, it is one of the most reliable of the natural, hormone-free methods. You only have to use additional contraception or avoid intercourse on the fertile days. Read here for more on the reliability and application of the symptothermal method.
 
 
 
 
  
 
 
The symptothermal method consists of analysing two ovulation symptoms. On the one hand, you measure your basal body temperature every morning, and on the other hand, you can either observe and analyse your cervical mucus or document the changes in your cervix.
 
 
 
 
 
Sources:
 
     
  •  1 Bundeszentrale für gesundheitliche Aufklärung (Hrsg.): Sichergehn. Verhütung für sie und ihn. Köln 2013. 
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  •  2 Malteser Arbeitsgruppe NFP (Hrsg.): Natürlich und sicher. Das Praxisbuch. 18. Auflage. Stuttgart 2011. 
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  •  3 Diedrich, K. et al.: Gynäkologie und Geburtshilfe. 2. Auflage, Heidelberg 2007. 
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  •  4 Raith-Paula, E. et al.: Natürliche Familienplanung heute. Modernes Zykluswissen für Beratung und Anwendung. 5. Auflage. Heidelberg 2013. 
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  •  5 Clinical evaluation in accordance with the European Medical Device Directive 93/42/EEC & MEDDEV 2.7.1. Cyclotest myWay und Cyclotest my Sense APP. 2019. 
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