Determining the Fertile Window when Preventing Pregnancy with the Sympto-thermal Method
This person is using the sympto-thermal method for pregnancy prevention. If all of the rules are properly followed, they must either abstain from intercourse or use a back-up method of birth control starting on cycle day 10 (when cervical fluid is first noticed) until cycle day 20, when the rules have been satisfied. They are using the First Five Days Rule and not the Doering Rule. Their fertile window begins on cycle day 13 with the appearance of cervical fluid, and they can consider themselves infertile starting in the evening on cycle day 19, in accordance with the Double-Check Rule.
Learn the rules of the sympto-thermal method to effectively prevent pregnancy naturally.