Evaluation of the effectiveness of selected natural fertility symptoms used for contraception: estimation of the Pearl index of Lady-Comp, Pearly and Daysy cycle computers based on 10 years of observation in the Polish market

Ginekol Pol. 2016;87(12):793-797. doi: 10.5603/GP.2016.0090.


Objectives: Cycle computers are medical devices which use sophisticated statistical methods in addition to a comprehensive on-board database. Their main function is to precisely indicate the fertile and infertile phases of the menstrual cycle, based on daily basal body temperature measurements. A recent medical research program aimed at evaluating the EFFECTIVENESS of cycle computers for contraceptive purposes was conducted.

Material and methods: This study was conducted between May and June 2016 on 3,450 Polish women. The Polish distributor sent an anonymous questionnaire to the participants. To date, 361 women, representing 17,322 cycles have returned accurately completed questionnaires.

Results: In the resultant group only 4 unintended pregnancies were observed, resulting in a Pearl index of 0.4989. This suggests that fewer than 5 in 1000 women, who use a cycle computer correctly over a period of one year, may become pregnant unintentionally. This result is slightly better than the results from 2010, when the Pearl index was 0.64.

Conclusions: The results obtained from the study indicate that the effectiveness of cycle computers for contraceptive purposes is comparable with other methods, such as hormonal contraception, and therefore cycle computers can be recommended for women who either cannot use or do not wish to use traditional contraception. These results confirm the effectiveness of using natural fertility symptoms, such as basal body temperature changes in the context of cycle computer technology for the purposes of contraception.

Keywords: contraception; cycle computer; pearl index; symptom-thermal method.

Publication types

  • Observational Study

MeSH terms

  • Adult
  • Body Temperature*
  • Contraception / methods*
  • Contraception Behavior
  • Female
  • Fertility / physiology*
  • Humans
  • Menstrual Cycle / physiology*
  • Natural Family Planning Methods / methods*
  • Ovulation Detection / methods*
  • Poland
  • User-Computer Interface
  • Young Adult