The Symptothermal Method of Natural Family Planning determines the fertile and infertile phases of the cycle by simultaneously observing two indicators in each phase: cervical secretion, basal temperature, and other indicators such as changes in the cervix. The method does not seem to us to be the most recommended to avoid pregnancy, but it is very effective for planning to become pregnant.
Symptothermal method
- In the preovulatory period, the cervical secretion parameter and a calculation based on information from previous cycles are used to determine the start of the fertile phase.
- The beginning of the postovulatory period of absolute infertility is determined by indicators of temperature and cervical secretion. The woman should record her temperature in basal conditions on the graph (after her longest rest, which is usually in the morning) in order to observe the temperature rise.
- Changes in the cervix can be used to confirm the information provided by these fertility indicators.
- As it is a double check method (several fertility indicators are used simultaneously), the Symptothermic method is more effective in practice than the Billings method.
- Theoretical efficacy: 99.6% (if only pregnancies that occur despite correctly following the application rules are taken into account).
- Practical efficiency: 97% (if pregnancies that occur when users make a mistake and do not follow the application rules correctly are also taken into account).