Lady Cycle makes no compromises with regard to efficacy and use-effectiveness. We implemented the symptothermal method developed by an international group of scientists in Europe.
This method combines your basal body temperature entries with your cervical mucus entries or with your cervix characteristics to determine your fertility state. If based on cervical mucus or cervix characteristics you could still be fertile, Lady Cycle will still show you as fertile.
You can also determine the end of the fertile period manually, if you would like to use a different method (see corresponding question in the section Android App).