Scientific studies

An independent US study published in 2016 by FACTS confirms sympto's superiority : 

The educational tool sympto® perfectly illustrates the symptothermal rules as they are discribed in the Manual The Complete Symptothermal Method. However, when Symptothermia (symptothermal Method) is used without sympto® in the old fashioned way, just with a BBT thermometer, a paper or electronic chart, we are in the world of the symptothermal schools  of the last 40 years. As a matter of fact, Symptothermia is not a contraception at all, it is neither a method for preventing pregnancy nor a birth control. Symptothermia is a natural conception regulation based on the conscious competence and free choice of a female person or a couple to manage the fertile window. 

Again: the educational tool sympto® is not a contraception app. It does not predict ovulation, neither does it predict the next menstruation and it does not work with statistics in order to "calclulate" the fertile and infertile days of the female cycle. sympto® is an educational tool which helps you to learn and to manage symptothermia.

sympto® has undergone studies that are visible below.

The English press release of the comparative study of 2013 is available here.

The 2014 study, published in a Swiss gynecological journal, is available here: info@gynäkologie, 4, 2015, 33- 35:

Full Comparative App-Study 2013, only in French

Full Comparative App-Study of 2014


The study of 2013 was published in The European Journal of Contraception and Reproductive Health, Vol. 19, Supplement 1, May 2014, p. 201.


A) below the most recent clinical studies: (The WHO studies of the eighties are completely outdated.)

  1. Here a recent summary of most of the studies:
    Osteopathic Family Physician (2013) 5, 2–8:
    Fertility awareness-based methods of family planning: A review of effectiveness for avoiding pregnancy using SORT, Michael D. Manhart, PhD, Marguerite Duane, MD, MHA, FAAFP, April Lind, MD, Irit Sinai, PhD, Jean Golden-Tevald. From the Couple to Couple League, Cincinnati, OH; Georgetown University, Washington, DC; Park Nicollett Clinic, Maple Grove, MN; and Morningstar Family Health Center, Clinton, NJ.
  2. Frank-Herrmann,P., Heil,J., Gnoth,C. et al (2007) The effectiveness of a fertility awareness based method to avoid pregnancy in relation to a couple's sexual behaviour during the fertile time: a prospective longitudinal study. Hum.Reprod., 22, 1310-1319.
  3. Frank-Herrmann P., Gnoth, C., Baur, S, Strowitzki T, and Freundl, G. Determination of the fertile window: Reproductive competence of women - European cycle databases. Gynecol.Endocrinol. 20(6), 305-312. 2005. Ref Type: Journal (Full)
  4. Frank-Herrmann P., Strowitzki T, Wischmann T, Gnoth, Ch, and Freundl, G. Fertility Awareness in der Hormonsprechstunde - ein Pilotprojekt an der Universität Heidelberg. Forschung für die Frau in einer neuen Welt(Deutsche Ges. für Gynäkologie und Geburtshilfe), PB.11.08. 9-12-2002. Springer. Ref Type: Art Work
  5. Frank-Herrmann,P., Freundl,G., Gnoth,C. et al (1997) Natural family planning with and without barrier method use in the fertile phase: efficacy in relation to sexual behavior: a German prospective long-term study. Adv.Contracept., 13, 179-189
  6. Freundl, G. The effectiveness of NFP, demonstrated on two ongoing studies, the German and the European study. IV. Symposium Internacional sobre Regulacion Natural de la Fertilidad (Asociasion Espanola de Profesores de Planificacion Fam. Nat.), 57-64. 1994. Universidad de Barcelona. Ref Type: Art Work
  7. Freundl,G. (2000) Natürliche Familienplanung und "nicht-hormonale Kontrazeption". Gynäkologe, 33, 679-688.
  8. Freundl,G. (2004) Natürliche Familienplanung. In Bender,H., Diedrich,K., and Künzel,W. (eds), Klinik der Frauenheilkunde und Geburtshilfe. Urban & Fischer, München , Jena, pp. 163-172
  9. Freundl,G. (1998) Kontrazeption per Computer. Hormonmesssystem Persona-- Studienergebnisse in Deutschland. (Contraception per computer. Hormone system persona--results of studies in Germany). Fortschritte Der Medizin, 116, 47-48
  10. Freundl,G., Frank-Herrmann P., Godehardt,E. et al (2003) Die Effektivität von Zyklusmonitoren zur Bestimmung des fertilen Fensters . Geburtshilfe.Frauenheilkd., 63
  11. Freundl,G., Godehardt,E., Kern,P.A. et al (2003) Estimated maximum failure rates of cycle monitors using daily conception probabilities in the menstrual cycle. Hum Reprod., 18, 2628-2633
  12. Freundl,G., Suberg,D., Flynn,A.M. et al. (1984) [Natural family planning (symptothermal method) and objective ovulation parameters--a pilot study] Naturliche Familienplanung (symptothermale Methode) und objektive Ovulationsparameter--eine Pilotstudie. Geburtshilfe. Frauenheilkd., 44, 368-374
  13. Gnoth, Ch, Godehardt, D, Godehardt, E., Frank-Herrmann P., and Freundl, G. Kumulative Schwangerschaftswahrscheinlichkeit in natürlichen Zyklen: eine prospektive Studie. Forschung für die Frau in einer neuen Welt (Deutsche Ges. für Gynäkologie und Geburtshilfe). 9-12-2002. Berlin, Heidelberg, Springer Verlag. Ref Type: Art Work
  14. Raith,E., Frank,P., and Freundl,G. (1999) Raith-Paula,E., Frank-Herrmann P., and Freundl,G. (eds), Natürliche Familienplanung heute mit ausführlicher Darstellung der Zykluscomputer. Springer, Berlin, 1-273
  15. Sottong,U., Bremme,M., and Freundl,G. (1992) Lactational amenorrhoea and lactational anovulation in 109 breastfeeding women. Advances In Contraception, 8, 269-270
  16. Sottong,U., Fortrie,C., Bremme,M. et al (1998) Kontrazeption in der Stillzeit Wie werden natürliche Methoden akzeptiert und angewandt? Sexualmedizin, 20, 244-250
  17. Zinaman,M. and Stevenson,W. (1991) Efficacy of the symptothermal method of natural family planning in lactating women after the return of menses. Am.J.Obstet.Gynecol., 165, 2037-2039
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